Optical filter comprising transparent support and filter layer containing dye and binder polymer

ABSTRACT

An optical filter comprises a transparent support and a filter layer. The filter layer contains a dye and a binder polymer. The dye is a methine dye in an aggregated form. The transparent support, the filter layer or an optional layer further contains a specific ultraviolet absorbing agent represented by the formula (I), (II), or (III).

This application claims priority under 35 U.S.C. §§119 and/or 365 to11-152823 and 11-252731 filed in Japan on May 31, 1999 and Sep. 7, 1999,respectively; the entire contents of which are hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention relates to an optical filter comprising atransparent support and a filter layer. In more detail, the inventionrelates to an optical filter covering a display surface of a displaydevice such as a liquid crystal display device (LCD), a plasma displaypanel (PDP), an electroluminescence display (ELD), a cathode-ray tube(CRT), a fluorescent indicator tube or a field emission display toimprove the color reproducibility of the display.

BACKGROUND OF THE INVENTION

A display device such as a liquid crystal display device (LCD), a plasmadisplay panel (PDP), an electroluminescence display (ELD), a cathode-raytube (CRT), a fluorescent indicator tube or a field emission displaydisplays a color image with a combination of the three primary colors(i.e., red, blue, green). However, it is very difficult (substantiallyimpossible) to use the ideal three primary colors. For example, theplasma display panel uses phosphors of the three primary colors, whichemit light containing an unnecessary component (in the wavelength regionof 560 to 620 nm). Therefore, it has been proposed to correct the colorbalance of the displayed image by an optical filter absorbing theunnecessary component. The optical filter for the color correction isdescribed in Japanese Patent Provisional Publication Nos.58(1983)-53904, 60(1985)-118748, 60(1985)-18749, 61(1986)-188501,3(1991)-231988, 5(1993)-203804, 5(1993)-205643, 7(1995)-307133,9(1997)-145918, 9(1997)-306366 and 10(1998)-26704.

The display device needs prevention of reflection as well as the colorcollection. On the screen of the display device, the surrounding sceneis often reflected to impair the contrast of the displayed image.Various anti-reflection films have been proposed to solve the problem ofreflection. The known anti-reflection layers are categorized into twotypes, namely evaporating (and depositing) layers and coating layers.The evaporating layers are superior to the coating layers in view ofoptical characteristics, but the coating layers are easily formedcompared with the evaporating layers.

The evaporating layers have been used as anti-reflection films forlenses of glasses or cameras. The layers are generally formed by avacuum deposition process, a spattering method, an ion plating method, aCVD method or a PVD method.

The coating layers can be formed by coating a dispersion of fineparticles and a binder. The coating layers are described in JapanesePatent Provisional Publication Nos. 59(1984)-49501, 59(1984)-50401,60(1985)-59250 and 7(1995)-48527.

The anti-reflection layers can be introduced into the optical filters.The optical filters having the anti-reflection layers are disclosed inJapanese Patent Provisional Publication Nos. 61(1986)-188501,5(1993)-205643, 9(1996)-145918, 9(1996)-306366 and 10(1997)-26704. Theoptical filter described in 61(1986)-188501, 5(1993)-205643,9(1996)-145918 or 9(1996)-306366 has a transparent support containing adye or a pigment so that the support functions as an optical filter.Further, the optical filter described in 10(1997)-26704 comprises acolored hard coating (surface hardening) layer provided between asupport and an anti-reflection layer, so that the hard coating layerfunctions as an optical filter.

SUMMARY OF THE INVENTION

A colored transparent support or a colored hard coating layer canfunction as an optical filter. However, it is difficult to incorporate adye or pigment into the support or the hard coating layer.

The transparent support is made of glass or plastics (usually,plastics). Therefore, the dye or pigment contained in the support musthave enough heat resistance to a high temperature in the productionprocess of the support.

The hard coating layer generally comprises a cross-linked polymer. Informing the layer, the polymer is cross-linked after coating a polymersolution. The dye or pigment added in the solution often fades at thecrosslinking reaction.

Many methine dyes have been researched in the field of silver halidephotography. The methine dyes have various absorption spectra. Themethine dye in an aggregated form has a sharp absorption peak (a narrowhalf width). The methine dyes have been developed to be contained in aphotographic material (usually in a gelatin layer). If the methine dyesare incorporated into the support or the hard coating layer, the dyesusually have problems of fading.

The applicants have tried to add the methine dyes not to the support orthe hard coating layer (which restricts the dyes or pigments), but in apolymer layer. The polymer layer can be formed under moderateconditions. Many photographic methine dyes can be contained in thepolymer layer, which functions as an optical filter. However, thepolymer layer does not protect the dyes, compared with the support andthe hard coating layer. Therefore, the methine dyes in an aggregatedform to be contained in the polymer layer are preferably improved indurability (particularly, light resistance). The methine dyes should beimproved without disturbing the function (color correction) of the dye.The dyes should also be improved without absorbing light for an imageemitted from the phosphors. Further, the dye should be improved withoutcoloring the image display device when the image is not displayed.

An object of the present invention is to provide an optical filterhaving a function of correcting color appropriately.

Another object of the invention is to provide an optical filter whichcan advantageously be used with a plasma display panel.

The present invention provides an optical filter which comprises atransparent support and a filter layer containing a dye and a binderpolymer, wherein the dye is a methine dye in an aggregated form, andwherein the transparent support, the filter layer or an optional layerfurther contains an ultraviolet absorbing agent represented by theformula (I), (II), (III), (IV), (V), (VI), (VII) or (VIII):

in which the benzene rings a and b may have a substituent group;

in which Ar¹ is an aryl group or an aromatic heterocyclic group; —L— isa single bond or —O—; and the benzene ring c may have a substituentgroup;

in which the benzene ring d and the triazine ring e may have asubstituent group; and the benzene ring d may be condensed with anotheraromatic ring or a heterocyclic ring;

in which the benzene rings f and g may have a substituent group;

in which Ar² is an aryl group or an aromatic heterocyclic group; R¹ ishydrogen or an alkyl group; and each of R² and R³ independently iscyano, —COR¹³, —COOR¹⁴, —CONR¹⁵R¹⁶, —SO₂R¹⁷ or —SO₂NR¹⁸R¹⁹, wherein eachof R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ independently is hydrogen, analkyl group, a substituted alkyl group or an aryl group, or R² and R³are combined to form a five-membered or six-membered ring;

in which each of R⁴ and R⁵ independently is hydrogen, an alkyl group oran aryl group, or R⁴ and R⁵ are combined to form a five-membered orsix-membered ring; and each of R⁶ and R⁷ independently is cyano, —COR²⁰,—COOR²¹, —CONR²²R²³, —SO₂R²⁴ or —SO₂NR²⁵R²⁶, wherein each of R²⁰, R²¹,R²², R²³, R²⁴, R²⁵ and R²⁶ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group, or R⁶ and R⁷ are combined toform a five-membered or six-membered ring;

in which R⁸ is an alkyl group, a substituted alkyl group or an arylgroup; each of R⁹ and R¹⁰ independently is cyano, —COR²⁷, —COOR²⁸,—CONR²⁹R³⁰, —SO₂R³¹ or —SO₂NR³²R³³, wherein each of R²⁷, R²⁸, R²⁹, R³⁰,R³¹, R³² and R³³ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group, or R⁹ and R¹⁰ are combined toform a five-membered or six-membered ring; —X˜Y— is —CR³⁴R³⁵—CR³⁶R³⁷— or—CR³⁸═CR³⁹—, wherein each of R³⁴, R³⁵, R³⁶, R³⁷, R³⁸ and R³⁹independently is hydrogen, an alkyl group or an aryl group, or R³⁸ andR³⁹ are combined to form a benzene or naphthalene ring; —Z— is —O—, —S—,—NR⁴⁰—, —CR⁴¹R⁴²— or —CH═Ch—, wherein R⁴⁰ is an alkyl group, asubstituted alkyl group or an aryl group, and each of R⁴¹ and R⁴²independently is hydrogen or an alkyl group; and n is 0 or 1;

in which each of R¹¹ and R¹² independently is hydrogen, an alkyl groupor an aryl group, or R¹¹ and R¹² are combined to form a five-membered orsix-membered ring; the benzene rings h and i may have a substituentgroup; and the benzene rings h and i may be condensed with anotheraromatic ring or a heterocyclic ring.

The ultraviolet absorbing agent preferably is an o-substituted phenolrepresented by the formula (I), (II) or (III).

The invention also provides a plasma display panel having a displaysurface covered with an optical filter which comprises a transparent anda filter layer containing a dye and a binder polymer, wherein the dye isa methine dye in an aggregated form, and wherein the transparentsupport, the filter layer or an optional layer further contains anultraviolet absorbing agent represented by the formula (I), (II), (III),(IV), (V), (VI), (VII) or (VIII).

The absorption maximum of the optical filter can easily be adjusted byusing a methine dye in an aggregated form. Further, the methine dye inthe aggregated form shows a sharp absorption peak (a narrow half width)appropriate for an image display device. However, the aggregated methinedye contained in a filter layer is unstable to an ultraviolet ray.

According to the study of the applicants, the compound represented bythe formula (I), (II), (III), (IV), (V), (VI), (VII) or (VIII) givesultraviolet resistance (durability against ultraviolet ray) to themethine dye in an aggregated form contained in an optical filter. Themethine dye is now improved in durability by using the compoundrepresented by the formula (I), (II), (III), (IV), (V), (VI), (VII) or(VIII), particularly the o-substituted phenol represented by the formula(I), (II) or (III) without disturbing the function (color correction) ofthe dye, without absorbing light for an image emitted from the phosphorsand without coloring the image display device when the image is notdisplayed.

A known ultraviolet absorbing agent usually have a problem of durabilityof the agent itself to an ultraviolet ray. In an optical filter or ananti-reflection film, which is continually exposed to strong lightcontaining ultraviolet ray, the ultraviolet absorbing agent should bestable to an ultraviolet ray to continue the ultraviolet absorbingfunction. The compound represented by the formula (I), (II), (III),(IV), (V), (VI), (VII) or (VIII), particularly the o-substituted phenolrepresented by the formula (I), (II) or (III) is stable to theultraviolet ray. Therefore, the ultraviolet absorbing agent can protectthe aggregated methine dye from the ultraviolet ray for a long term.

According to the present invention, various known methine dyes forphotographic materials can be used in the optical filter. The absorptionspectra of many methine dyes have been well studied in the field ofphotographic materials. Therefore, the color of the displayed image canbe easily corrected by selecting a methine dye having an appropriateabsorption spectrum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) to 1(e) show sectional views schematically illustratingvarious embodiments of an optical filter, which comprises a filter layerand a transparent support.

FIGS. 2(a) to 2(d) show sectional views schematically illustratingvarious embodiments of an optical filter, which comprises a filterlayer, a transparent support and an anti-reflection layer in this order.

FIGS. 3(a) to 3(d) show sectional views schematically illustratingembodiments of an optical filter, which comprises a transparent support,a filter layer and an anti-reflection layer in this order.

FIG. 4 shows a spectrum of an optical filter prepared in Example 17.

DETAILED DESCRIPTION OF THE INVENTION

[Layered structure]

FIG. 1 shows sectional views schematically illustrating variousembodiments of an optical filter, which comprises a filter layer and atransparent support.

The embodiment of FIG. 1(a) comprises a filter layer (2) and atransparent support (1) in this order. The filter layer (2) contains anultraviolet absorbing agent.

The embodiment of FIG. 1(b) comprises a filter layer (2) and atransparent support (1) in this order. The transparent support (1)contains an ultraviolet absorbing agent.

The embodiment of FIG. 1(c) comprises an ultraviolet absorbing layer(3), a filter layer (2) and a transparent support (1) in this order. Theultraviolet ray absorbing layer (3) contains an ultraviolet rayabsorbing agent.

The embodiment of FIG. 1(d) comprises a filter layer (2), an ultravioletabsorbing layer (3) and a transparent support (1) in this order. Theultraviolet absorbing layer (3) contains an ultraviolet absorbing agent.

The embodiment of FIG. 1(e) comprises a filter layer (2), a transparentsupport (1) and an ultraviolet absorbing layer (3) in this order. Theultraviolet absorbing layer (3) contains an ultraviolet ray absorbingagent.

As is shown in FIG. 1, the ultraviolet absorbing agent can beincorporated into any layers of the optical filter.

The ultraviolet ray causing the problems is emitted from a light sourceoutside the image display device. Accordingly, the ultraviolet absorbingagent should be arranged outside the methine dye or mixed with the dye.Therefore, an element (a layer or a support) containing the ultravioletabsorbing agent is arranged outside form the filter layer in the imagedisplay device, or the agent is added to the filter layer. The opticalfilter can be so placed on the display device that the transparentsupport is arranged outside the device or that the filter layer isarranged outside the device. Therefore, there is no specific limitationwith respect to arrangement of the ultraviolet absorbing agent in viewof the optical filter (not in view of the image display device), as isshown in FIG. 1.

FIG. 2 shows sectional views schematically illustrating variousembodiments of an optical filter, which comprises a filter layer, atransparent support and an anti-reflection layer in this order.

The embodiment of FIG. 2(a) comprises a filter layer (2), a transparentsupport (1) and a low refractive index layer (4) in this order. Thelayer (4) and the support (1) satisfy the condition of n₄<n₁ in which n₄and n₁ represent the refractive indexes of the layer (3) and the support(1) respectively.

The embodiment of FIG. 2(b) comprises a filter layer (2), a transparentsupport (1), a hard coating layer (5) and a low refractive index layer(4) in this order.

The embodiment of FIG. 2(c) comprises a filter layer (2), a transparentsupport (1), a hard coating layer (5), a high refractive index layer (6)and a low refractive index layer (4) in this order. The layers (4) and(6) and the support (1) satisfy the condition of n₄<n₁<n₆ in which n₄,n₁ and n₆ represent the refractive indexes of the layer (4), the support(1) and the layer (6) respectively.

The embodiment of FIG. 2(d) comprises a filter layer (2), a transparentsupport (1), a hard coating layer (5), a middle refractive index layer(7), a high refractive index layer (6) and a low refractive index layer(4) in this order. The layers (4), (6) and (7) and the support (1)satisfy the condition of n₄<n₁<n₇<n₆ in which n₄, n₁, n₇ and n₆represent the indexes of the layer (4), the support (1), the layer (7)and the layer (6) respectively.

An ultraviolet absorbing agent can be contained in the filter layer (2),the transparent support (1), the hard coating layer (5), the middlerefractive index layer (7), the high refractive index layer (6), the lowrefractive index layer (4) or an optically formed layer (ultravioletabsorbing layer). The ultraviolet absorbing layer can be arrangedbetween two elements (layer or support), or arranged as the uppermostlayer or the lowermost layer. There is no specific limitation withrespect to arrangement of the ultraviolet absorbing agent, as isdescribed about the optical filter shown in FIG. 1.

FIG. 3 shows sectional views schematically illustrating variousembodiments of an optical filter, which comprises a transparent support,a filter layer and an anti-reflection layer in this order.

The embodiment of FIG. 3(a) comprises a transparent support (1), afilter layer (2) and a low refractive index layer (4) in this order.With respect to the refractive index, the layer (4) and the support (1)satisfy the same condition as that of the embodiment of FIG. 2(a).

The embodiment of FIG. 3(b) comprises a transparent support (1), afilter layer (2), a hard coating layer (5) and a low refractive indexlayer (4) in this order.

The embodiment of FIG. 3(c) comprises a transparent support (1), afilter layer (2), a hard coating layer (5), a high refractive indexlayer (6) and a low refractive index layer (4) in this order. Withrespect to the refractive index, the layers (4) and (6) and the support(1) satisfy the same condition as that of the embodiment of FIG. 2(c).

The embodiment of FIG. 3(d) comprises a transparent support (1), afilter layer (2), a hard coating layer (5), a middle refractive indexlayer (7), a high refractive index layer (6) and a low refractive indexlayer (4) in this order. With respect to the refractive index, thelayers (4), (6) and (7) and the support (1) satisfy the same conditionas that of the embodiment of FIG. 2(d).

There is no specific limitation with respect to arrangement of theultraviolet absorbing agent, as is described about FIGS. 1 & 2.

[Ultraviolet absorbing agent]

The ultraviolet absorbing agent preferably is a compound of notdisturbing the function (color correction) of the dye, not absorbinglight for an image emitted from the phosphors and not coloring the imagedisplay device when the image is not displayed.

The ultraviolet absorbing agent preferably has the absorption maximum ofthe longest wavelength within the wavelength region of 300 to 390 nm.The absorption maximum of the longest wavelength is more preferably inthe range of 310 to 380 nm, and most preferably in the range of 320 to360 nm.

The absorption at the wavelength of 50 nm longer than the absorptionmaximum is preferably less than 10%, more preferably less than 7%, andmost preferably less than 5% of the absorption at the absorptionmaximum.

An absorption spectrum of an ultraviolet absorbing agent is measured ina solution, since it is difficult to measure the spectrum in an opticalfilter because other components such as dispersed particles disturb thespectrum. Accordingly, an ultraviolet absorbing agent in a solutionpreferably satisfies the above-described absorption. The solvent of thesolution is water (in the case of a water-soluble ultraviolet absorbingagent) or ethyl acetate (in the case of an oil-soluble ultravioletabsorbing agent).

Further, the ultraviolet absorbing agent is preferably stable toultraviolet ray.

The present invention uses a compound represented by the formula (I),(II), (III), (IV), (V), (VI), (VII) or (VIII), and preferably ano-substituted phenol represented by the formula (I), (II) or (III) as anultraviolet absorbing agent to satisfy the above-described requirements.

In the formula (I), the benzene rings a and b may have a substituentgroup.

Examples of the substituent groups include a halogen atom (F, Cl, Br),nitro, cyano, sulfo, an alkyl group, a substituted alkyl group, analkenyl group, a substituted alkenyl group, an aryl group, aheterocyclic group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R, —SO₂—R,—NR², —NH—CO—R, —NH—SO₂—R, —CO—NR², —SO₂—NR₂, —NH—CO—O—R and —NH—CO—NR₂.R is hydrogen, an alkyl group, a substituted alkyl group, an alkenylgroup, a substituted alkenyl group or an aryl group. Sulfo and carboxyl(—CO—O—R when R is hydrogen) can form a salt. In the presentspecification, sulfo and carboxyl can form a salt.

In the present specification, an alkyl group preferably has 1 to 20carbon atoms. An alkyl group of a chain structure is preferred to acyclic alkyl group. The alkyl group can have a branched chain. Examplesof the alkyl groups include methyl, ethyl, isopropyl, butyl, sec-butyl,tert-butyl, pentyl, tert-pentyl, hexyl, octyl, 2-ethylhexyl, tert-octyl,decyl, dodecyl, hexadecyl, octadecyl, cyclopropyl, cyclopentylcyclohexyl and bicyclo[2,2,2]octyl.

In the present specification, an alkyl moiety of a substituted alkylgroup is the same as the above-described alkyl group. Examples of thesubstituent groups of the substituted alkyl groups include a halogenatom, nitro, a heterocyclic group, cyano, sulfo, an aryl group, —O—R,—S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R, —SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R,—CO—NR₂, —SO₂—NR², —NH—CO—O—R and —NH—CO—NR₂. R is hydrogen, an alkylgroup, a substituted alkyl group, an alkenyl group, a substitutedalkenyl group or an aryl group.

In the present specification, an alkenyl group preferably has 2 to 20carbon atoms. An alkenyl group of a chain structure is preferred to acyclic alkenyl group. The alkenyl group can have a branched chain.Examples of the alkenyl groups include allyl, 2-butenyl and oleyl.

In the present specification, an alkenyl moiety of a substituted alkenylgroup is the same as the above-described alkyl group. Examples of thesubstituent groups of the substituted alkenyl groups include a halogenatom, nitro, a heterocyclic group, cyano, sulfo, an aryl group, —O—R,—S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R, —SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R,—CO—NR₂, —SO₂—NR₂, —NH—CO—O—R and —NH—CO—NR₂. R is hydrogen, an alkylgroup, a substituted alkyl group, an alkenyl group, a substitutedalkenyl group or an aryl group.

In the present specification, an aryl group preferably has 6 to 10carbon atoms. Examples of the aryl groups include phenyl and naphthyl.

The aryl group can have a substituent group. Examples of the substituentgroups include a halogen atom, nitro, a heterocyclic group, cyano,sulfo, an aryl group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R,—SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R, —CO—NR₂, —SO₂—NR₂, —NH—CO—O—R and—NH—CO—NR₂. R is hydrogen, an alkyl group, a substituted alkyl group, analkenyl group, a substituted alkenyl group or an aryl group.

In the present specification, a heterocyclic group preferably has afive-membered or six-membered heterocyclic ring. Examples of theheterocyclic groups include furan ring, thiophene ring, indole ring,pyrrole ring, pyrazole ring, imidazole ring and pyridine ring.

The heterocyclic group can have a substituent group. Examples of thesubstituent groups include a halogen atom, nitro, a heterocyclic group,cyano, sulfo, an aryl group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R,—SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R, —CO—NR₂, —SO₂—NR₂, —NH—CO—O—R and—NH—CO—NR₂. R is hydrogen, an alkyl group, a substituted alkyl group, analkenyl group, a substituted alkenyl group or an aryl group.

In the formula (II), Ar¹ is an aryl group or an aromatic heterocyclicgroup. Ar¹ preferably is an aryl group.

The aromatic heterocyclic group preferably has a five-membered orsix-membered heterocyclic ring. Examples of the aromatic heterocyclicgroups include furan ring, thiophene ring, indole ring, pyrrole ring,pyrazole ring, imidazole ring and pyridine ring.

The aromatic heterocyclic group can have a substituent group. Examplesof the substituent groups include a halogen atom, nitro, a heterocyclicgroup, cyano, sulfo, an aryl group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R,—SO—R, —SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R, —CO—NR₂, —SO₂—NR₂, —NH—CO—O—Rand —NH—CO—NR². R is hydrogen, an alkyl group, a substituted alkylgroup, an alkenyl group, a substituted alkenyl group or an aryl group.

In the formula (II), —L— is a single bond or —O—, and preferably is asingle bond.

In the formula (II), the benzene ring c may have a substituent group.

Examples of the substituent groups include a halogen atom (F, Cl, Br),nitro, cyano, sulfo, an alkyl group, a substituted alkyl group, analkenyl group, a substituted alkenyl group, an aryl group, aheterocyclic group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R, —SO₂—R,—NR₂, —NH—CO—R, —NH—SO₂—R, —CO—NR₂, —SO₂—NR₂, —NH—CO—O—R and —NH—CO—NR₂.R is hydrogen, an alkyl group, a substituted alkyl group, an alkenylgroup, a substituted alkenyl group or an aryl group.

In the formula (III), the benzene ring d and the triazine ring e mayhave a substituent group.

Examples of the substituent groups include a halogen atom (F, Cl, Br),nitro, cyano, sulfo, an alkyl group, a substituted alkyl group, analkenyl group, a substituted alkenyl group, an aryl group, aheterocyclic group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R, —SO₂—R,—NR², —NH—CO—R, —NH—SO₂—R, —CO—NR², —SO₂—NR₂, —NH—CO—O—R and —NH—CO—NR₂.R is hydrogen, an alkyl group, a substituted alkyl group, an alkenylgroup, a substituted alkenyl group or an aryl group.

The substituent group of the triazine ring e preferably is an arylgroup, more preferably is phenyl, and most preferably iso-hydroxyphenyl.

In the formula (III), the benzene ring d may be condensed with anotheraromatic ring or a heterocyclic ring. Examples of the aromatic ringsinclude benzene ring and naphthalene ring. Examples of the heterocyclicrings include furan ring, thiophene ring, indole ring, pyrrole ring,pyrazole ring, imidazole ring and pyridine ring.

In the formula (IV), the benzene rings f and g may have a substituentgroup.

Examples of the substituent groups include a halogen atom (F, Cl, Br),nitro, cyano, sulfo, an alkyl group, a substituted alkyl group, analkenyl group, a substituted alkenyl group, an aryl group, aheterocyclic group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R, —SO₂—R,—NR², —NH—CO—R, —NH—SO₂—R, —CO—NR₂, —SO₂—NR₂, —NH—CO—O—R and —NH—CO—NR₂.R is hydrogen, an alkyl group, a substituted alkyl group, an alkenylgroup, a substituted alkenyl group or an aryl group.

In the formula (V), Ar² is an aryl group or an aromatic heterocyclicgroup.

The aromatic heterocyclic group preferably has a five-membered orsix-membered heterocyclic ring. Examples of the aromatic heterocyclicgroups include furan ring, thiophene ring, indole ring, pyrrole ring,pyrazole ring, imidazole ring and pyridine ring.

The aromatic heterocyclic group can have a substituent group. Examplesof the substituent groups include a halogen atom, nitro, a heterocyclicgroup, cyano, sulfo, an aryl group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R,—SO—R, —SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R, —CO—NR₂, —SO₂—NR₂, —NH—CO—O—Rand —NH—CO—NR₂. R is hydrogen, an alkyl group, a substituted alkylgroup, an alkenyl group, a substituted alkenyl group or an aryl group.

In the formula (V), R¹ is hydrogen or an alkyl group.

In the formula (V), each of R² and R³ independently is cyano, —COR¹³,—COOR¹⁴, —CONR¹⁵R¹⁶, —SO₂R¹⁷ or —SO₂NR¹⁸R¹⁹. Each of R¹³, R¹⁴, R¹⁵, R¹⁶,R¹⁷, R¹⁸ and R¹⁹ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group. R² and R³ can be combined toform a five-membered or six-membered ring.

At least one of R¹⁵ and R¹⁶ preferably is hydrogen. At least one of R¹⁸and R¹⁹ preferably is hydrogen.

The five-membered or six-membered ring formed by combining R² and R³preferably functions as an acidic nucleus of a methine dye. Examples ofthe five-membered or six-membered rings, which can function as acidicnuclei, include 2-pyrazoline-5-one ring, pyrazolidine-2,4-dione ring,rhodanine ring, hydantoin ring, 2-thiohydantoin ring, 4-thiohydantoinring, 2,4-oxazolidinedione, isooxazolone ring, barbituric acid ring,thiobarbituric acid ring, indanedione ring, hydroxypyridone ring,furanone ring, 1,3-cyclohexanedione ring and meldramic acid ring.

The five-membered or six-membered ring can have a substituent group.Examples of the substituent groups include a halogen atom, nitro, aheterocyclic group, cyano, sulfo, an aryl group, —O—R, —S—R, —CO—R,—CO—O—R, —O—CO—R, —SO—R, —SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R, —CO—NR₂,—SO₂—NR₂, —NH—CO—O—R and —NH—CO—NR₂. R is hydrogen, an alkyl group, asubstituted alkyl group, an alkenyl group, a substituted alkenyl groupor an aryl group.

In the formula (VI), each of R⁴ and R⁵ independently is hydrogen, analkyl group or an aryl group, or R⁴ and R⁵ are combined to form afive-membered or six-membered ring.

Examples of the five-membered or six-membered rings include pyrrolidinering, piperidine ring and morpholine ring.

The five-membered or six-membered ring can have a substituent group.Examples of the substituent groups include a halogen atom, nitro, aheterocyclic group, cyano, sulfo, an aryl group, —O—R, —S—R, —CO—R,—CO—O—R, —O—CO—R, —SO—R, —SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R, —CO—NR₂,—SO₂—NR², —NH—CO—O—R and —NH—CO—NR₂. R is hydrogen, an alkyl group, asubstituted alkyl group, an alkenyl group, a substituted alkenyl groupor an aryl group.

In the formula (VI), each of R⁶ and R⁷ independently is cyano, —COR²⁰,—COOR²¹, —CONR²²R²³, —SO₂R²⁴ or—SO₂NR²⁵R²⁶. Each of R²⁰, R²¹, R²², R²³,R²⁴, R²⁵ and R²⁶ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group. R⁶ and R⁷ can be combined toform a five-membered or six-membered ring.

At least one of R²² and R²³ preferably is hydrogen. At least one of R²⁵and R²⁶ preferably is hydrogen.

The five-membered or six-membered ring formed by combining R⁶ and R⁷preferably functions as an acidic nucleus of a methine dye. Examples ofthe five-membered or six-membered rings, which can function as acidicnuclei, include 2-pyrazoline-5-one ring, pyrazolidine-2,4-dione ring,rhodanine ring, hydantoin ring, 2-thiohydantoin ring, 4-thiohydantoinring, 2,4-oxazolidinedione, isooxazolone ring, barbituric acid ring,thiobarbituric acid ring, indanedione ring, hydroxypyridone ring,furanone ring, 1,3-cyclohexanedione ring and meldramic acid ring.

The five-membered or six-membered ring can have a substituent group.Examples of the substituent groups include a halogen atom, nitro, aheterocyclic group, cyano, sulfo, an aryl group, —O—R, —S—R, —CO—R,—CO—O—R, —O—CO—R, —SO—R, —SO₂—R, —NR², —NH—CO—R, —NH—SO₂—R, —CO—NR₂,—SO₂—NR₂, —NH—CO—O—R and —NH—CO—NR₂. R is hydrogen, an alkyl group, asubstituted alkyl group, an alkenyl group, a substituted alkenyl groupor an aryl group.

In the formula (VII), R⁸ is an alkyl group, a substituted alkyl group oran aryl group.

In the formula (VII), each of R⁹ and R¹⁰ independently is cyano, —COR²⁷,—COOR²⁸, —CONR²⁹R³⁰, —SO₂R³¹ or —SO₂NR³²R³³. Each of R²⁷, R²⁸, R²⁹, R³⁰,R³¹, R³² and R³³ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group. R⁹ and R¹⁰ can be combined toform a five-membered or six-membered ring.

At least one of R²⁹ and R³⁰ preferably is hydrogen. At least one of R³²and R³³ preferably is hydrogen.

The five-membered or six-membered ring formed by combining R⁹ and R¹⁰preferably functions as an acidic nucleus of a methine dye. Examples ofthe five-membered or six-membered rings, which can function as acidicnuclei, include 2-pyrazoline-5-one ring, pyrazolidine-2,4-dione ring,rhodanine ring, hydantoin ring, 2-thiohydantoin ring, 4-thiohydantoinring, 2,4-oxazolidinedione, isooxazolone ring, barbituric acid ring,thiobarbituric acid ring, inanedione ring, hydroxypyridone ring,furanone ring, 1,3-cyclohexanedione ring and meldramic acid ring.

The five-membered or six-membered ring can have a substituent group.Examples of the substituent groups include a halogen atom, nitro, aheterocyclic group, cyano, sulfo, an aryl group, —O—R, —S—R, —CO—R,—CO—O—R, —O—CO—R, —SO—R, —SO₂—R, —NR₂, —NH—CO—R, —NH—SO₂—R, —CO—NR₂,—SO₂—NR₂, —NH—CO—O—R and —NH—CO—NR₂. R is hydrogen, an alkyl group, asubstituted alkyl group, an alkenyl group, a substituted alkenyl groupor an aryl group.

In the formula (VII), —X˜Y— is —CR³⁴R³⁵—CR³⁶R³⁷— or —CR³⁸═CR³⁹—. Each ofR³⁴, R³⁵, R³⁶, R³⁷, R³⁸ and R³⁹ independently is hydrogen, an alkylgroup or an aryl group. R³⁸ and R³⁹ can be combined to form a benzene ornaphthalene ring.

In the formula (VII), —Z— is —O—, —S—, —NR⁴⁰—, —CR⁴¹R⁴²— or —CH═CH—. R⁴⁰is an alkyl group, a substituted alkyl group or an aryl group. Each ofR⁴¹ and R⁴² independently is hydrogen or an alkyl group.

In the formula (VII), n is 0 or 1.

In the formula (VIII), each of R¹¹ and R¹² independently is hydrogen, analkyl group or an aryl group. R¹¹ and R¹² can be combined to form afive-membered or six-membered ring.

In the formula (VIII), the benzene rings h and i may have a substituentgroup.

Examples of the substituent groups include a halogen atom (F, Cl, Br),nitro, cyano, sulfo, an alkyl group, a substituted alkyl group, analkenyl group, a substituted alkenyl group, an aryl group, aheterocyclic group, —O—R, —S—R, —CO—R, —CO—O—R, —O—CO—R, —SO—R, —SO₂—R,—NR₂, —NH—CO—R, —NH—SO₂—R, —CO—NR₂, —SO₂—NR², —NH—CO—O—R and —NH—CO—NR₂.R is hydrogen, an alkyl group, a substituted alkyl group, an alkenylgroup, a substituted alkenyl group or an aryl group.

In the formula (VIII), the benzene rings h and i may be condensed withanother aromatic ring or a heterocyclic ring. Examples of the aromaticrings include benzene ring and naphthalene ring. Examples of theheterocyclic rings include furan ring, thiophene ring, indole ring,pyrrole ring, pyrazole ring, imidazole ring and pyridine ring.

The ultraviolet absorbing agent preferably is a compound represented bythe formula (I), (II), (III) or (IV), more preferably is ano-substituted phenol represented by the formula (I), (II) or (III), andmost preferably is an o-substituted phenol represented by the formula(I) or (III).

Examples of the compounds represented by the formula (I), (II), (III),(IV), (V), (VI), (VII) and (VIII) are shown below.

(I-1)-(I-13)

(I-1) Ra:  —H, Rb:  —H, Rc:  -t-C₈H₁₇ (I-2) Ra:  —H, Rb:  -t-C₄H₉, Rc: —CH₂CH₂COOC₈H₁₇ (I-3) Ra:  —H, Rb:  —C(CH₃)₂—Ph, Rc:  -t-C₈H₁₇ (I-4)Ra:  —H, Rb:  —C(CH₃)₂—Ph, Rc:  —C(CH₃)₂—Ph (I-5) Ra:  —H, Rb:  —H, Rc: —CH₃ (I-6) Ra:  —H, Rb:  -t-C₅H₁₁, Rc:  -t-C₅H₁₁ (I-7) Ra:  —H, Rb: -t-C₅H₁₁, Rc:  —H (I-8) Ra:  —H, Rb:  —NHCOCH(CH₃)₂, Rc:  —CH₃ (I-9)Ra:  —Cl, Rb:  -t-C₄H₉, Rc:  -t-C₄H₉ (I-10) Ra:  —OCH_(3,) Rb:  -t-C₄H₉,Rc:  —CH₃ (I-11) Ra:  —Cl, Rb:  -t-C₄H₉, Rc:  —CH₂CH₂COOC₈H₁₇ (I-12) Ra: —H, Rb:  —C₁₂H₂₅, Rc:  —CH₃ (I-13) Ra:  —SC₁₂H₂₅, Rb:  -t-C₄H₉, Rc: -t-C₄H₉ (Remark) Ph:  Phenyl (I-14)

(I-15)

(I-16)

(I-17)

(I-18)

(I-19)

(I-20)

(I-21)

(II-1)-(II-8)

(II-1) Ra:  —OCH₃, Rb:  —H (II-2) Ra:  —OC₈H₁₇, Rb:  —H (II-3) Ra: —OCH₂—Ph, Rb:  —H (II-4) Ra:  —OCH₂—COO—C₂H_(5,) Rb:  —H (II-5) Ra: —OH, Rb:  —CO—Ph (II-6) Ra:  —O—(CH₂)₃—COOH, Rb:  —H (II-7) Ra:  —OH,Rb:  —H (II-8) Ra:  —OCH₃, Rb:  —SO₃H (Remark) Ph:  Phenyl  (II-9)

(II-10)

(II-11)

(II-12)

(II-13)

(II-14)

(II-15)

(II-16)

(II-17)

(II-18)

(III-1)

(III-2)

(III-3)

(III-4)

(III-5)

(III-6)

(III-7)

(III-8)

(III-9)

(III-10)

(III-11)

(III-12)

(III-13)

(III-14)

(III-15)

(III-16)

(III-17)

(III-18)

(III-19)

(III-20)

(III-21)

(III-22)

(III-23)

(III-24)

(III-25)

(III-26)

(III-27)

(III-28)

(III-29)

(III-30)

(III-31)

(III-32)

(III-33)

(III-34)

(III-35)

(III-36)

(III-37)

(III-38)

(III-39)

(III-40)

(III-41)

(III-42)-(III-50)

(III-42) Ra:  —C₂H₅, Rb:  —CH₂—CHOH—CH₂—OC₄H₉ (III-43) Ra: —CH₂—CHOH—CH₂—OC₄H₉, Rb:  —CH₂—CHOH—CH₂—OC₄H₉ (III-44) Ra:  —C₂H₅, Rb: —CH(CH₃)—COO—C₂H₅ (III-45) Ra:  —CH(CH₃)—COO—C₂H₅, Rb: —CH(CH₃)—COO—C₂H₅ (III-46) Ra:  —CH₂—CH(C₂H₅)—C₄H₉, Rb: —CH₂—CH(C₂H₅)—C₄H₉ (III-47) Ra:  —C₄H₉, Rb:  —C₄H₉ (III-48) Ra: —CH₂—COO—C₂H₅, Rb:  —CH₂—COO—C₂H₅ (III-49) Ra:  —C₂H₅, Rb:  —C₈H₁₇(III-50) Ra:  —C₂H₅, Rb:  —CH₂—COO—C₂H₅ (IV-1)

(IV-2)

(V-1)-(V-4)

(V-1) Ra:  —OCH₃, Rb:  —COOH (V-2) Ra:  —OCH₃, Rb:  —COONa (V-3) Ra: —OCH₃, Rb:  —COO—C₁₀H₂₁ (V-4) Ra:  —CH₃, Rb:  —COO—C₁₂H₂₅ (V-5)

(V-6)

(V-7)

(V-8)

(V-9)

(V-10)

(V-11)

(V-12)

(VI-1)

(VI-2)

(VI-3)

(VI-4)

(VI-5)

(VI-6)

(VI-7)

(VII-1)

(VII-2)

(VII-3)

(VII-4)

(VII-5)

(VII-6)

(VII-7)

(VII-8)

(VIII-1)

(VIII-2)

(VIII-3)

The compounds represented by the formula (I), (II), (III), (IV), (V),(VI), (VII) or (VIII) can be synthesized by referring to variousdocuments (Japanese Patent Publication Nos. 36(1961)-10466,48(1973)-5496, 48(1973)-30492, 55(1980)-36984, 55(1980)-125875, JapanesePatent Provisional Publication Nos. 46(1971)-3335, 47(1972)-10537,51(1976)-56620, 53(1978)-128333, 58(1983)-181040, 58(1983)-214152,58(1983)-221844, 59(1984)-19945, 63(1988)-53544, 6(1994)-211813,7(1995)-258228, 8(1996)-53427, 8(1996)239368, 10(1998)-115898,10(1998)-147577, 10(1998)-182621, 8(1996)-501291, U.S. Pat. Nos.2,719,086, 3,698,707, 3,707,375, 3,754,919, 4,220,711, 5,298,380,5,500,332, 5,585,228, 5,814,438, British Patent No. 1,198,337, EuropeanPatent Nos. 323408A, 520938A, 521823a, 530135A, 531258A).

The structure, physical property and function of a representativeultraviolet absorbing agent is described in Andreas Valet, LightStabilizers for Paint, Vincents.

A polymer having repeating units containing a chemical structurecorresponding to the formula (I), (II), (III), (IV), (V), (VI), (VII) or(VIII) can also be used as an ultraviolet absorbing agent.

Examples of the repeating units containing a chemical structurecorresponding to the formula (I), (II), (III), (V) or (VI) are shownbelow.

A homopolymer consisting of the above-described repeating unit can beused as the ultraviolet absorbing agent. A copolymer comprising two ormore repeating units can also be used as the ultraviolet absorbingagent. Further, a copolymer comprising another repeating unit can beused as the ultraviolet absorbing agent. Examples of the other repeatingunits are shown below.

Examples of the copolymers comprising the repeating units containing achemical structure corresponding to the formula (I), (II), (III), (V) or(VI) and the other repeating units are shown below. In the followingexamples, the number corresponds to the above-described repeating unit.The ratio of the repeating unit means mol %.

P-1: -(II-p1)₅₀-(IX-p1)₅₀—

P-2: -(II-p1)₃₀-(IX-p1)₇₀—

P-3: -(II-p1)₁₀-(IX-p1)₇₀-(IX-p2)₂₀—

P-4: -(II-p1)₁₀-(IX-p1)₅₀-(IX-p2)₄₀—

P-5: -(I-p1)₅₀-(IX-p3)₅₀—

P-6: -(I-p2)₃₂-(IX-p4)₆₅-(IX-p5)₃—

P-7: -(I-p3)₃₃-(IX-p2)₆₇—

P-8: -(I-p4)₄₈-(IX-p2)₄₈-(IX-p5)₄—

P-9: -(I-p5)₄₈-(IX-p2)₄₈-(IX-p5)₄—

P-10: -(V-p1)₇₀-(IX-p1)₃₀—

P-11: -(VI-p2)₈₀-(IX-P1)₂₀—

P-12: -(VI-p3)₇₀-(IX-p2)₃₀—

P-13: -(III-p1)₂₀-(IX-p2)₈₀—

A polymer comprising repeating units containing a chemical structurecorresponding to the formula (I) is described in Japanese PatentProvisional Publication Nos. 47(1972)-560, 58(1983)-185677,62(1987)-24247, 63(1988)-55542, 3(1991)-139590, 4(1992)-193869,6(1994)-82962, 8(1996)-179464 and European Patent No. 747755.

A polymer comprising repeating units containing a chemical structurecorresponding to the formula (II) is described in Japanese PatentProvisional Publication Nos. 63(1988)-35660, 2(1990)-180909.

A polymer comprising repeating units containing a chemical structurecorresponding to the formula (III) is described in European Patent No.706083.

A polymer comprising repeating units containing a chemical structurecorresponding to the formula (V) is described in Japanese PatentPublication No. 63(1988)-53541 and Japanese Patent ProvisionalPublication No. 4(1992)-500228.

A polymer comprising repeating units containing a chemical structurecorresponding to the formula (VI) is described in Japanese PatentPublication No. 1(1989)-53455, Japanese Patent Provisional PublicationNo. 61(1986)-189530 and European Patent No. 27242.

A polymer comprising repeating units containing a chemical structurecorresponding to the formula (VII) is described in Japanese PatentProvisional Publication No. 63(1988)-53543.

A polymer comprising repeating units containing a chemical structurecorresponding to another ultraviolet absorbing agent is described inJapanese Patent Provisional Publication Nos. 47(1972)-192,61(1986)-169831, 63(1988)-53543, 63(1988)-53544, 63(1988)-56651, andEuropean Patent No. 343246.

The ultraviolet absorbing agent can be incorporated into a structuralelement (layer or support) of an optical filter according to variousmethods. The ultraviolet absorbing agent can be directly added to acomponent of the element where the ultraviolet absorbing agent ismiscible with the component. The ultraviolet absorbing agent can bedissolved in an auxiliary solvent, which is miscible with the component,and the solution can be added to the element. The ultraviolet absorbingagent can be dispersed in a high boiling point organic solvent or apolymer, and the dispersion can be added to the element.

The high boiling point organic solvent has a boiling point preferably ofhigher than 180° C., and more preferably of higher than 200° C. Themelting point of the high boiling point organic solvent is preferablylower than 150° C., and more preferably lower than 100° C.

Examples of the high boiling point organic solvents include a phosphoricester, a phosphonic ester, a benzoic ester, a phthalic ester, a fattyacid ester, a carbonic ester, amide, ether, a halogenated hydrocarbon,an alcohol and paraffin. A phosphoric ester, a phosphonic ester, abenzoic ester and a fatty acid ester are preferred.

The high boiling point organic solvent preferably has a refractive indexsimilar to the refractive index of a binder (e.g., gelatin) of a layerto which the solvent and the ultraviolet absorbing agent are to beadded. The refractive index of the solvent is preferably lower than1.50, and more preferably in the range of 1.43 to 1.48.

The ultraviolet absorbing agent can be added to an optical filter byreferring to Japanese Patent Provisional Publication Nos.58(1983)-209735, 63(1988)-264748, 4(1992)-191851, 8(1996)-272058 andBritish Patent No. 2016017A.

Two or more ultraviolet absorbing agents can be used in combination. Acombination of two (preferably three) ultraviolet absorbing agents canabsorb an ultraviolet ray of a wide wavelength range. Further, thedispersion of the ultraviolet absorbing agent can be stabilized by usingtwo or more ultraviolet absorbing agents in combination.

The amount of the ultraviolet absorbing agent is preferably in the rangeof 0.001 to 10 g/m², more preferably in the range of 0.05 to 5 g/m², andmost preferably in the range of 0.1 to 2 g/m². The absorption of theultraviolet ray at 360 nm is preferably more than 0.6, more preferablymore than 1.0, and most preferably more than 1.5.

[Transparent support]

Examples of the materials for the support include cellulose esters(e.g., diacetyl cellulose, triacetyl cellulose, propionyl cellulose,butyryl cellulose, acetyl propionyl cellulose, nitrocellulose),polyamides, polycarbonates, polyesters (e.g., polyethyleneterephthalate, polyethylene naphthalate, poly-1,4-cyclohexanedimethyleneterephthalate, polyethylene-1,2-diphenoxyethane-4,4,-dicarboxylate,polybutylene terephthalate), polystyrenes (e.g., syndiotacticpolystyrene), polyolefins (e.g., polypropylene, polyethylene,polymethylpentene), polymethyl methacrylate, syndiotactic polystyrene,polysulfone, polyethersulfone, polyetherketone, polyether imide andpolyoxyethylene. Triacetyl cellulose (TAC), polycarbonates andpolyethylene terephthalate are preferred.

The transparent support preferably has a transmittance of more than 80%,and more preferably more than 86%. The haze of the support is preferablyin the range of less than 2.0%, and more preferably less than 1.0%. Thesupport preferably has a refractive index of 1.45 to 1.70.

The support may contain an infrared absorbing agent. The amount of theinfrared absorbing agent is preferably in the range of 0.01 to 20 wt. %and more preferably 0.05 to 10 wt. % based on the total weight of thesupport. The support may further contain particles of an inert inorganiccompound as a slipping agent. Examples of the inorganic compound includeSiO₂, TiO₂, BaSO₄, CaCO₃, talc and kaolin.

The support may be subjected to surface treatment. Examples of thesurface treatment include chemical treatment, mechanical treatment,corona discharge treatment, flame treatment, UV treatment,high-frequency treatment, glow discharge treatment, active plasmatreatment, laser treatment, mixed acid treatment and ozone-oxidationtreatment. Preferred treatments are glow discharge treatment, UVtreatment, corona discharge treatment and flame treatment. Glowdischarge treatment and UV treatment are particularly preferred. Forenhancing the adhesion between the support and the layer providedthereon, an undercoating layer may be provided on the support.

[Undercoating layer]

An undercoating layer is preferably provided between the transparentsupport and the filter layer.

The undercoating layer may contain a polymer having a glass transitiontemperature in the range of −60° C. to 60° C. or a polymer compatiblewith the polymer of the filter layer. On the support surface opposite tothe filter layer side, another undercoating layer may be provided toenhance the adhesion between the support and the layers thereon (e.g.,anti-reflection layers, hard coating layer). Further, anotherundercoating layer can be provided to improve the affinity between theoptical filter and the adhesive agent for fixing the optical filter ontoa display device.

The undercoating layer has a thickness preferably in the range of 2 nmto 20 μm more in the range of 5 nm to 5 μm, and most preferably in therange of 50 nm to 5 μm.

The undercoating layer containing a polymer having a glass transitiontemperature in the range of −60° C. to 60° C. unites the filter layer tothe transparent support with the adhesion of the polymer. The polymerhaving a glass transition temperature in the range of −60° C. to 60° C.can be prepared by polymerization or copolymerization of vinyl chloride,vinylidene chloride, vinyl acetate, butadiene, neoprene, styrene,chloroprene, acrylic ester, methacrylic ester, acrylonitrile or methylvinyl ether. The glass transition temperature is preferably not higherthan 20° C., more preferably not higher than 15° C., further preferablynot higher than 10° C., furthermore preferably not higher than 5° C.,and most preferably not higher than 0° C.

The undercoating layer having a rough surface also unites the filterlayer to the transparent support. On the rough surface of theundercoating layer, the filter layer is provided. The undercoating layerhaving a rough surface can be easily formed by applying a polymer latex.The polymer latex has a mean particle size preferably in the At range of0.02 to 3 μm, and more preferably in the range of 0.05 to 1 μm.

Examples of the polymer compatible with that of the filter layer includeacrylic resins, cellulose derivatives, gelatin, casein, starch,polyvinyl alcohol, soluble nylon and polymer latex.

Two or more undercoating layers can be provided on the support.

The undercoating layer can contain other components such as a solventfor swelling the support, a matting agent, a surface active agent, anantistatic agent, a coating aid and a curing agent.

[Filter layer]

The filter layer preferably has a thickness preferably in the range of0.1 μm to 5 cm.

The filter layer preferably gives an absorption spectrum having themaximum in the wavelength region of 560 nm (green) to 620 nm (red).

The absorption maximum in the wavelength range of 560 to 620 nm isarranged to selectively cut a sub-band, which degrades purity of redfluorescence. The absorption maximum in the wavelength range of 560 to620 nm can further cut an unnecessary light about 595 nm, which isemitted by excitation of neon gas in PDP. In the optical filter of thepresent invention, the unnecessary light can be selectively cut withoutinfluence on the color of the green fluorescence. The influence on thegreen fluorescence can be further reduced by obtaining a sharp peak inthe absorption spectrum. The absorption maximum in the wavelength rangeof 560 to 620 nm has a half-width preferably in the range of 10 to 120nm, more preferably in the range of 15 to 100 nm, further preferably inthe range of 20 to 70 nm, and most preferably in the range of 30 to 50nm.

The filter layer contains a methine dye and a polymer binder.

The methine dye is used in an aggregated form. The methine dye can beclassified into a cyanine dye, a merocyanine dye, an arylidene dye, astyryl dye and an oxonol dye. The methine dyes are defined by thefollowing formulas.

Cyanine dye: Bs═Lo—Bo

Merocyanine dye: Bs═Le═Ak

Arylidene dye: Ak═Lo—Ar

Styryl dye: Bo—Le—Ar

Oxonol dye: Ak═Lo—Ae

in which Bs is a basic nucleus; Bo is an onium form of a basic nucleus;Ak is an acidic nucleus of a keto type; Ae is an acidic nucleus of anenol type; Ar is an aromatic nucleus; Lo is a methine chain consistingof an odd number of methines; and Le is a methine chain consisting of aneven number of methines.

The methine dye preferably is a cyanine dye or an oxonol dye, and morepreferably is a cyanine dye.

The cyanine dye is preferably represented by the formula (X).

In the formula (X), each of Z¹ and Z² independently is a group ofnon-metallic atoms forming a five-membered or six-memberednitrogen-containing heterocyclic ring. The nitrogen-containingheterocyclic ring may be condensed with other heterocyclic, aromatic oraliphatic rings. Examples of the nitrogen-containing heterocyclic ringinclude oxazole ring, isoxazole ring, benzoxazole ring,naphthoxazolering, thiazole ring, benzothiazole ring, naphthothiazolering, indolenine ring, benzoindolenine ring, imidazole ring,benzimidazole ring, naphthoimidazole ring, quinoline ring, pyridinering, pyrrolopyridine ring, furopyrrole ring, indolizine ring,imidazoquinoxaline ring and quinoxaline ring. A five-memberednitrogen-containing heterocyclic ring is preferred to a six-memberedring. A five-membered nitrogen-containing heterocyclic ring ispreferably condensed with benzene or naphthalene ring. A particularlypreferred ring is benzimidazole ring.

The nitrogen-containing heterocyclic ring and the ring condensedtherewith can have a substituent group. Examples of the substituentgroups include an alkyl group, a cycloalkyl group, an aralkyl group, analkoxy group, an aryl group, an aryloxy group, a halogen atom (Cl, Br,F), an alkoxycarbonyl group, an alkylthio group, an arylthio group, anacyl group, an acyloxy group, amino, a substituted amino group, an amidogroup, a sulfonamido group, ureido, a substituted ureido group,carbamoyl, a substituted carbamoyl group, sulfamoyl, a substitutedsulfamoyl group, an alkylsulfonyl group, an arylsulfonyl group,hydroxyl, cyano, nitro, sulfo, carboxyl and a heterocyclic group. Eachof sulfo and carboxyl can be in the form of a salt.

The alkyl group can have a branched structure. The alkyl grouppreferably has 1 to 20 carbon atoms. The alkyl group can have asubstituent group. Examples of the substituent groups include a halogenatom (Cl, Br, F), an alkoxy group (e.g., methoxy, ethoxy), hydroxyl andcyano. Examples of the alkyl groups (including the substituted alkylgroups) include methyl, ethyl, propyl, t-butyl, hydroxyethyl,methoxyethyl, cyanoethyl and trifluoromethyl.

Examples of the cycloalkyl groups include cyclopentyl and cyclohexyl.

The aralkyl group preferably has 7 to 20 carbon atoms. Examples of thearalkyl groups include benzyl and 2-phenethyl.

The alkoxy group can have a branched structure. The alkoxy grouppreferably has 1 to 12 carbon atoms. The alkoxy group can have asubstituent group. Examples of the substituent groups include an alkoxygroup and hydroxyl. Examples of the alkoxy groups (including thesubstituted alkoxy groups) include methoxy, ethoxy, methoxyethoxy andhydroxyethoxy.

The aryl group preferably is phenyl. The aryl group can have asubstituent group. Examples of the substituent groups include an alkylgroup, an alkoxy group, a halogen atom and nitro. Examples of thesubstituted aryl groups include p-tolyl, p-methoxyphenyl, o-chlorophenyland m-nitrophenyl.

The aryloxy group preferably is phenoxy. The aryloxy group can have asubstituent group. Examples of the substituent groups include an alkylgroup, an alkoxy group and a halogen atom. Examples of the substitutedaryloxy groups include p-chlorophenoxy, p-methylpheoxy ando-methoxyphenoxy.

The alkoxycarbonyl group preferably has 2 to 20 carbon atoms. Examplesof the alkoxycarbonyl groups include methoxy carbonyl andethoxycarbonyl.

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of thealkylthio groups include methylthio, ethylthio and butylthio.

The arylthio group preferably is phenylthio. The arylthio group can havea substituent group. Examples of the substituent group include an alkylgroup, an alkoxy group and carboxyl. Examples of the substitutedarylthio groups include p-methylphenylthio, p-methoxyphenylthio ando-carboxyphenylthio.

The acyl group preferably has 2 to 20 carbon atoms. Examples of the acylgroups include acetyl and butyryl.

The acyloxy group preferably has 2 to 20 carbon atoms. Examples of theacyloxy groups include acetoxy and butyryloxy.

The substituted amino group preferably has 1 to 20 carbon atoms.Examples of the substituted amino groups include methylamino, anilinoand triazinylamino.

The amido group preferably has 2 to 20 carbon atoms. Examples of theamido groups include acetamido, propionamido and isobutanamido.

The sulfonamido group preferably has 1 to 20 carbon atoms. Examples ofthe sulfonamido groups include methanesulfonamido andbenzenesulfonamido.

The substituted ureido group preferably has 2 to 20 carbon atoms.Examples of the substituted ureido groups include 3-methylureido and3,3-dimethylureido.

The substituted carbamoyl group preferably has 2 to 20 carbon atoms.Examples of the substituted carbamoyl groups include methylcarbamoyl anddimethylcarbamoyl.

The substituted sulfamoyl group preferably has 1 to 20 carbon atoms.Examples of the substituted sulfamoyl groups include dimethylsufamoyland diethylsulfamoyl.

The alkylsulfonyl group preferably has 1 to 20 carbon atoms. Examples ofthe alkylsulfonyl groups include methanesulfonyl.

The arylsulfonyl group preferably is benzenesulfonyl.

Examples of the heterocyclic groups include pyridyl and thienyl.

In the formula (X), each of R¹ and R² independently is an alkyl group,an alkenyl group, an aralkyl group or an aryl group. Each of R¹ and R²preferably is an alkyl group

The alkyl group can have branched structure. The alkyl group preferablyhas 1 to 20 carbon atoms and may have a substituent group. Examples ofthe substituent groups include a halogen atom (Cl, Br, F), analkoxycarbonyl group (e.g., methoxycarbonyl, ethoxycarbonyl), hydroxyl,sulfo and carboxyl. Each of sulfo and carboxyl may be in the form of asalt.

The alkenyl group preferably has 2 to 10 carbon atoms. Examples of thealkenyl group include 2-pentenyl, vinyl, allyl, 2-butenyl and1-propenyl. The alkenyl group may have a substituent group. Examples ofthe substituent groups are the same as those of the alkyl group.

The aralkyl group preferably has 7 to 12 carbon atoms. Examples of thearalkyl group include benzyl and phenethyl. The aralkyl group can have asubstituent group. Examples of the substituent groups include an alkylgroup (e.g., methyl, ethyl, propyl), an alkoxy group (e.g., methoxy,ethoxy), an aryloxy group (e.g., phenoxy, p-chlorophenoxy), a halogenatom (Cl, Br, F), an alkoxycarbonyl group (e.g., ethoxycarbonyl), acarbon halide group (e.g., trifluoromethyl), an alkylthio group (e.g.,methylthio, ethylthio, butylthio), an arylthio group (e.g., phenylthio,o-carboxyphenylthio), cyano, nitro, amino, an alkylamino group(methylamino, ethylamino), an amido group (e.g., acetamido,propionamido), an acyloxy group (e.g., acetoxy, butyryloxy), hydroxyl,sulfo, and carboxyl. Each of sulfo and carboxyl may be in the form of asalt.

Examples of the aryl group include phenyl and naphthyl. The aryl groupcan have a substituent group. Examples of the substituent groups are thesame as those of the aralkyl group.

In the formula (X), L¹ is a methine chain consisting of an odd number ofmethines. The number is preferably 1, 3, 5 or 7, and more preferably 3or 5.

The methine chain can have a substituent group. In the case of that, thesubstituent is preferably placed at the centered methine (i.e.,meso-position) of the chain. Examples of the substituent groups includean alkyl group, an alkoxy group, an aryloxy group, a halogen atom, analkoxycarbonyl group, a carbon halide group, an alkylthio group, anarylthio group, cyano, nitro, amino, an alkylamino group, an amidogroup, an acyloxy group, hydroxyl, sulfo and carboxyl. Two substituentgroups can be combined with each other to form a five-membered orsix-membered ring.

In the formula (X), each of a, b, and c independently is 0 or 1. Each ofa and b is preferably 0. In the case where the cyanine dye has ananionic substituent group (e.g., sulfo, carboxyl) to form an inner salt,c is 0.

In the formula (X), X represents an anion. Examples of the anion includea halide ion (e.g., Cl⁻, Br⁻, I⁻), p-toluenesulfonate ion, ethylsulfateion, PF₆ ⁻, BF₄ ⁻, and ClO₄ ⁻.

The oxonol dye is preferably represented by the formula (XI).

In the formula (XI), each of Y¹ and Y² independently is a group ofnon-metallic atoms forming an aliphatic ring or a heterocyclic ring. Theheterocyclic ring is preferred to the aliphatic ring. Examples of thealiphatic rings include indanedione ring. Examples of the heterocyclicrings include 5-pyrazolone ring, oxazolone ring, barbituric acid ring,pyridone ring, rhodanine ring, pyrazolidinedione ring andpyrazolopyridone ring. The aliphatic ring or the heterocyclic ring canhave a substituent group. Examples of the substituent groups are thesame as those of the substituent groups of the nitrogen-containingheterocyclic group of Z¹ or Z² in the formula (X).

In the formula (XI), L³ is a methine chain consisting of an odd numberof methines. The number is preferably 3, 5 or 7 (more preferably 3). Themethine chain can have a substituent group. The substituent group ispreferably placed at the centered methine (i.e., meso-position) of thechain. Examples of the substituent are the same as those of thesubstituent groups for the methine chain in the formula (X). Twosubstituent groups can be combined with each other to form afive-membered or six-membered ring.

In the formula (XI), Xa is proton or a cation. In the case that Xa isproton, the proton and the neighboring oxygen form hydroxyl. Examples ofthe cations include an alkali metal ion (e.g., Na⁺, K⁺), ammonium ion,triethylammonium ion, tributylammonium ion, pyridinium ion,tetrabutylammonium ion and an onium ion.

Examples of the methine dyes are shown below.

(1)-(10)

 (1) Ra: —CH₃, Rb: —Cl, Rc: —Cl, X: Na  (2) Ra: —CH₃, Rb: —Cl, Rc: —CF₃,X: K  (3) Ra: —CH₃, Rb: —H, Rc: —Cl, X: K  (4) Ra: —CH₃, Rb: —H, Rc:—CONH₂, X: Na  (5) Ra: —C₂H₅, Rb: —Cl, Rc: —Cl, X: Na  (6) Ra: —n-C₃H₇,Rb: —Cl, Rc: —Cl, X: Na  (7) Ra: —C₂H₄OC₂H₅, Rb: —Cl, Rc: —Cl, X: Na (8) Ra: —C₂H₄OH, Rb: —Cl, Rc: —Cl, X: Na  (9) Ra: —CH₂—Ph, Rb: —Cl, Rc:—Cl, X: K (10) Ra: —Ph, Rb: —Cl, Rc: —Cl, X: K (Remark) Ph: Phenyl(11)-(15)

(11) Ra: —C₂H₄SO₃—, Rb: —Cl, Rc: —Cl, X: K (12) Ra: —C₃H₆SO₃—, Rb: —Cl,Rc: —CF₃—, X: Na (13) Ra: —CH₂CH₂CH(CH₃)SO₃—, Rb: —H, Rc: —CN, X: Na(14) Ra: —C₂H₄SO₃—, Rb: —H, Rc: —CN, X: (C₂H₅)₃HN (15) Ra: —C₄H₈SO₃—,Rb: —H, Rc: —CN, X: K (16)

(17)

(18)

(19)-(29)

(19) Ra: —CH₃, Rb: —Ph, Z: —S— (20) Ra: —C₂H₅, Rb: —Ph, Z: —S— (21) Ra:—C₂H₄OCH₃, Rb: —Ph, Z: —S— (22) Ra: —Ph, Rb: —Ph, Z: —S— (23) Ra:—CH₂—Ph, Rb: —Ph, Z: —S— (24) Ra: —CH₃, Rb: —Cl, Z: —S— (25) Ra: —CH₃,Rb: —Cl, Z: —O— (26) Ra: —C₂H₅, Rb: —Ph, Z: —O— (27) Ra: —C₂H₅, Rb: —Cl,Z: —Se— (28) Ra: —C₂H₅, Rb: —Cl, Z: —C(CH₃)₂— (29) Ra: —CH₃, Rb: —Ph, Z:—Se— (Remark) Ph: Phenyl (30)-(33)

(30) Ra: —H, Rb: —C₃H₆SO₃—, X: (C₂H₅)₃HN (31) Ra: —SO₃—, Rb: —C₃H₆SO₃—,X: 2K (32) Ra: —SO₃—, Rb: —C₃H₆SO₃—, X: 2Na (33) Ra: —SO₃—, Rb:—CH₂CH₂CH(CH₃)SO₃—, X: 2K (34)-(41)

(34) Ra: —C₃H₆SO₃—, Rb: —C₃H₆SO₃—, Rc: —H, Rd: —Cl, Re: —C₂H₅ (35) Ra:—C₄H₈SO₃—, Rb: —C₄H₈SO₃—, Rc: —H, Rd: —Cl, Re: —C₂H₅ (36) Ra: —C₂H₄SO₃—,Rb: —C₄H₈SO₃—, Rc: —Cl, Rd: —Cl, Re: —C₂H₅ (37) Ra: —C₂H₄SO₃—, Rb:—C₂H₄SO₃—, Rc: —CH₃, Rd: —CH₃, Re: —C₂H₅ (38) Ra: —C₄H₈SO₃—, Rb:—C₄H₈SO₃—, Rc: —CH₃, Rd: —CH₃, Re: —C₂H₅ (39) Ra: —C₄H₈SO₃—, Rb:—C₃H₆SO₃—, Rc: —H, Rd: —Ph, Re: —C₂H₅ (40) Ra: —C₄H₈SO₃—, Rb: —C₄H₈SO₃—,Rc: —H, Rd: —OCH₃, Re: —CH₃ (41) Ra: —C₄H₈SO₃—, Rb: —C₄H₈SO₃—, Rc: —H,Rd: —Cl, Re: —CH₃ (Remark) Ph: Phenyl (42)-(44)

(42) Ra: —C₃H₆SO₃—, Rb: —C₃H₆SO₃—, Rc: —H (43) Ra: —C₃H₆SO₃—, Rb:—C₃H₆SO₃—, Rc: —CH₃ (44) Ra: —C₄H₈SO₃—, Rb: —C₄H₈SO₃—, Rc: —C₂H₅(45)-(47)

(45) Ra: —C₄H₈SO₃—, Rb: —H (46) Ra: —C₄H₈SO₃—, Rb: —CH₃ (47) Ra:—C₃H₆SO₃—, Rb: —H (48)-(50)

(48) n: 1 (49) n: 2 (50) n: 3 (51)

(52)

(53)

(54)

(55)

(56)

(57)

(58)

(59)

(60)-(63)

(60) Ra: —H, Rb: —H, M: H (61) Ra: —H, Rb: —H, M: (C₂H₅)₃HN (62) Ra:—OH, Rb: —H, M: (C₂H₅)₃HN (63) Ra: —H, Rb: —OH, M: (C₂H₅)₃HN (64)

(65)

The methine dyes can be synthesized by referring to the descriptions ofF. M. Harmer, Heterocyclic Compounds Cyanine Dyes and Related Compounds,John Wiley and Sons, New York, London, 1964 and Japanese PatentProvisional Publication No. 6(1994)-313939.

In the present invention, the methine dye is used in an aggregated form.

A methine dye in an aggregated form usually has a J-band and a sharpabsorption peak in its spectrum. The aggregated form of the dye and theJ-band are described in Photographic Science and Engineering Vol. 18,No. 323-335 (1974). The absorption maximum of a methine dye can beshifted to a long wavelength region by changing the non-aggregated formto the aggregated form. Therefore, it can be determined by measuring anabsorption maximum whether a dye contained in a filter layer is in anaggregated form or not.

In the present specification, the aggregated form means that thewavelength of the absorption maximum of the aggregated form is longerthan the wavelength of the absorption maximum of the same dye in asolution, and the difference between the absorption maximums is largerthan 40 nm. The difference between the absorption maximums is preferablylarger than 45 nm, more preferably larger than 50 nm, and mostpreferably larger than 60 nm.

The transmittance at the absorption maximum in the wavelength range of560 to 620 nm is preferably in the range of 0.01 to 80%.

Some methine dyes can be prepared as an aggregated form merely bydissolving the dyes in water. The aggregated form is usually obtained byadding gelatin or salt (e.g., barium chloride, ammonium chloride, sodiumchloride) to an aqueous solution of a dye. The aggregated form ispreferably obtained by adding gelatin to an aqueous solution of a dye.

The aggregated form can also be obtained as a solid fine particledispersion. The fine particles can be prepared by means of known mills.Examples of the mill include a ball mill, a vibrating mill, a planetaryball mill, a sand mill, a colloid mill, a jet mill and a roller mill. Avertical or horizontal dispersing machine (described in Japanese PatentProvisional Publication No. 52(1977)-92716 and International Patent No.88/074794) is preferred.

The dispersing process can be carried out in the presence of anappropriate medium (e.g., water, alcohol). In that case, it is preferredto use a dispersing surface active agent. As the surface active agent,an anionic surface active agent (described in Japanese PatentProvisional Publication No. 52(1977)-92716 and International Patent No.88/074794) is preferably used. If necessary, an anionic polymer or anonionic or cationic surface active agent may be used.

The powdery fine particles of the dye can be prepared by the steps ofdissolving the dye in an appropriate solvent and adding a bad solvent toprecipitate the particles. In that case, the aforementioned surfaceactive agents are also employable. The fine particles can also beprecipitated by adjusting the pH value. The obtained fine particles arealso in the aggregated form.

The filter layer contains the methine dye preferably in an amount of0.01 mg per m² to 10 g per m², and more preferably in an amount of 1 mgper m² to 1 g per m².

Two or more dyes in the aggregated from can be used in combination. Themethine dye in the aggregated from can be used in combination withanother dye.

The filter layer preferably has the absorption maximum in the wavelengthrange of 500 to 550 nm (green) as well as the above-described absorptionmaximum in the wavelength range of 560 to 620 nm (green to red). In thecase that the methine dye in the aggregated from can be used incombination with another dye, the methine dye in the aggregated formpreferably has the absorption maximum in the wavelength range of 560 to620 nm and another dye preferably has the absorption maximum in thewavelength range of 500 to 550 nm. Another dye is preferably in anon-aggregated from. In the present specification, the non-aggregatedform means that the difference in the wavelength between the absorptionmaximum of the aggregated form and the absorption maximum of the samedye in a solution is not larger than 40 nm.

The transmittance at the absorption maximum in the wavelength range of500 to 550 nm is preferably in the range of 30 to 85%. The transmittanceat the absorption maximum in the wavelength range of 500 to 550 nm ispreferably larger than the transmittance at the absorption maximum inthe wavelength range of 560 to 620 nm. Further, the half-width of theabsorption maximum in the wavelength range of 500 to 550 nm ispreferably larger than the half-width of the absorption maximum in thewavelength range of 560 to 620 nm.

A squarylium dye, a triphenylmethane dye, an arylidene dye, an oxonoldye, an azo dye, an azomethine dye, an anthraquinone dye, a cyanine dye,a merocyanine dye or xanthene dye can be used as a dye having anabsorption maximum in the wavelength range of 500 to 550 nm. The dyesare described in U.S. Pat. Nos. 2,274,782, 3,471,293, 3,379,533. Thefilter layer can contain a pigment having an absorption maximum in thewavelength range of 500 to 550 nm in place of the dye.

The filter layer can further contain a dye having the an absorptionmaximum in the other wavelength range (other than 500 to 550 nm and 560to 620 nm). For example, the filter layer can contain a near infraredabsorbing dye. Examples of the near infrared absorbing dyes include acyanine dye (described in Japanese Patent Provisional Publication No.9(1997)-96891), a metal chelate dye, an aminium dye, a diimmonium dye, aquinone dye, a squarylium dye (described in Japanese Patent ProvisionalPublication Nos. 9(1997)-90547, 10(1998)-204310) and various methinedyes. The near infrared absorbing dyes are also described in Dyes(written in Japanese), 61[4]215-226 (1988) and Chemical Industries(written in Japanese, May, 1986).

The filter layer preferably contains two or more dyes in combination toobtain the absorption maximums in the ultraviolet region (400 nm orless), the visible region (500 to 620 nm) and the near infrared region(700 nm or more). Where the filter layer contains two or more dyes as isdescribed above, the optical filter can have two or more functions ofimproving reproducibility of an image, improving stability to light,preventing the display device from coloring when the image is notdisplayed, and preventing malfunction of a remote controller using anear infrared ray.

The filter layer contains a binder polymer. Examples of the polymerinclude natural polymers (e.g., gelatin, cellulose derivatives, alginicacid), and synthesized polymers (e.g., polymethyl methacrylate,polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinylchloride, styrene-butadiene copolymer, polystyrene, polycarbonate,water-soluble polyimide). Hydrophilic polymers (e.g., theabove-mentioned natural polymers, polyvinyl butyral, polyvinylpyrrolidone, polyvinyl alcohol, water-soluble polyimide) are preferred,and gelatin is particularly preferred.

The filter layer may contain an anti-fading agent, which stabilizes thedye. Examples of the anti-fading agent include hydroquinone derivatives(described in U.S. Pat. Nos. 3,935,016 and 3,982,944), hydroquinonediether derivatives (described in U.S. Pat. No. 4,254,216 and JapanesePatent Provisional Publication No. 55(1980)-21004), phenol derivatives(described in Japanese Patent Provisional Publication No.54(1979)-145530), spiroindane or methylenedioxybenzene derivatives(described in British Patent Publication Nos. 2,077,455, 2,062,888 andJapanese Patent Provisional Publication No. 61(1986)-90155), chroman,spirochroman or coumaran derivatives (described in U.S. Pat. Nos.3,432,300, 3,573,050, 3,574,627, 3,764,337 and Japanese PatentProvisional Publication Nos. 52(1977)-152225, 53(1978)-20327,53(1978)-17729, and 61(1986)-90156), hydroquinone monoether orp-aminophenol derivatives (described in British Patent Publication Nos.1,347,556, 2,066,975, Japanese Patent Publication No. 54(1979)-12337,and Japanese Patent Provisional Publication No. 55(1980)-6321), andbisphenol derivatives (described in U.S. Pat. No. 3,700,455, andJapanese Patent Publication No. 48(1973)-31625).

As the anti-fading agent, metal complexes (described in U.S. Pat. No.4,245,018 and Japanese Patent Provisional Publication No.60(1985)-97353) can be used to improve the stability of the dye againstlight or heat. Further, a singlet oxygen quencher is also usable as theanti-fading agent for improving the light resistance of the dye.Examples of the singlet oxygen quencher include nitroso compounds(described in Japanese Patent Provisional Publication No.2(1990)-300288), diimmonium compounds (described in U.S. Pat. No.465,612), nickel complexes (described in Japanese Patent ProvisionalPublication No. 4(1992)-146189) and anti-oxidizing agents (described inEuropean Patent Publication No. 820057A).

[Anti-reflection layers]

The optical filter can have an anti-reflection layer. The optical filterhaving the anti-reflection layer serves as an anti-reflection film. Asthe anti-reflection layer, a low refractive index layer is essential.The refractive index of the low refractive index layer is lower thanthat of the support, and is preferably in the range of 1.20 to 1.55(more preferably, 1.30 to 1.55).

The low refractive index layer has a thickness preferably of 50 to 400nm, and more preferably of 50 to 200 nm.

Various kinds of low refractive index layer have been proposed, and areemployable for the invention. Examples of them include a layercomprising fluorine-contained polymer of low refractive index (disclosedin Japanese Patent Provisional Publication Nos. 57(1982)-34526,3(1991)-130103, 6(1994)-115023, 8(1996)-313702, and 7(1995)-168004), alayer formed by sol-gel method (disclosed in Japanese Patent ProvisionalPublication Nos. 5(1993)-208811, 6(1994)-299091, and 7(1995)-168003),and a layer containing fine particles (disclosed in Japanese PatentPublication No. 60(1985)-59250, and Japanese Patent ProvisionalPublication Nos. 5(1993)-13021, 6(1994)-56478, 7(1995)-92306, and9(1997)-288201). The low refractive index layer containing fineparticles may further contain micro voids among the particles. The voidratio in that layer is preferably in the range of 3 to 50 vol. %, andmore preferably 5 to 35 vol. %.

Besides the low refractive index layer, layers having higher refractiveindexes (i.e., middle and high refractive index layers) are preferablyprovided to reduce the reflection in a wide wavelength region.

The high refractive index layer has a refractive index preferably in therange of 1.65 to 2.40, and more preferably in the range of 1.70 to 2.20.The middle refractive index layer has a refractive index between thoseof the low and high refractive index layers. The refractive index ispreferably in the range of 1.50 to 1.90, and more preferably in therange of 1.55 to 1.70.

Each of the middle and high refractive index layers has a thicknesspreferably in the range of 5 nm to 100 μm, more preferably in the rangeof 10 nm to 10 μm, and most preferably in the range of 30 nm to 1 μm.The haze of each layer is preferably in the range of not more than 5%,more preferably not more than 3%, further preferably not more than 1%.

The middle and high refractive index layers can be formed from a binderpolymer having a relatively high refractive index. Examples of thatbinder polymer include polystyrene, styrene copolymer, polycarbonate,melamine resin, phenol resin, epoxy resin, and a polyurethane derivedfrom the reaction between cyclic (alicyclic or aromatic) isocyanate andpolyol. Further, other polymers having cyclic (aromatic, heterocyclic oralicyclic) groups and polymers substituted with a halogen atom exceptfluorine also have high refractive indexes. The polymer may be preparedby polymerization of monomers having double bonds for radical hardening.

For a higher refractive index, inorganic fine particles may be dispersedin the binder polymers. The inorganic fine particles preferably have arefractive index of 1.80 to 2.80. As the materials for the particles,metal oxides and sulfides are preferred. Examples of them includetitanium dioxide (rutile, mixed crystal of rutile/anatase, anatase,amorphous structure), tin oxide, indium oxide, zinc oxide, zirconiumoxide, and zinc sulfide. Preferred materials are titanium oxide, tinoxide, and zirconium oxide. The inorganic fine particles may containother elements, as well as those oxides or sulfides of main component.The “main component” here means the component contained in the largestcontent (wt. %). Examples of the other elements include Ti, Zr, Sn, Sb,Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, P, and S.

The middle and high refractive index layers may be formed from liquid orsoluble film-formable inorganic materials. Examples of the materialsinclude alkoxides of various elements, salts of organic acids,coordination compounds (e.g., chelate compounds), and active inorganicpolymers.

The surface of the anti-reflection layer (i.e., the low refractive indexlayer) can be made to show anti-glare performance (which prevents thesurface from reflecting the surrounding scene by scattering the incidentlight). For example, the anti-reflection layer may be formed on a finelyroughened surface of a transparent film. Otherwise, the surface of theanti-reflection layer may be roughened by means of an embossing roll.The haze of the anti-reflection layer having such surface is generallyin the range of 3 to 30%.

[Electromagnetic wave shielding layer]

A layer having an effect of shielding an electromagnetic wave has asurface resistance preferably in the range of 0.1 to 500 Ω/m², and morepreferably in the range of 0.1 to 10 Ω/m². The layer is preferablytransparent because the layer is provided on an optical filter. Theelectromagnetic wave shielding layer preferably is a layer known as atransparent electroconductive layer.

The transparent electroconductive layer preferably is a metallic thinfilm or a metal oxide thin film. The metal for the metallic filmpreferably is a noble metal, more preferably is gold, silver, palladiumor alloy thereof, and most preferably is an alloy of gold with silver.The content of silver in the alloy is preferably more than 60 wt. %. Themetal oxide preferably is SnO₂, ZnO, ITO or In₂O₃.

The metallic thin film can be laminated with the metal oxide thin film.In the lamination, the metal oxide film can protect metallic film fromoxidation, and the transparency of visible light can be increased. Themetal oxide laminated with the metallic film preferably is divalent,trivalent or tetravalent metal oxide (e.g., zirconium oxide, titaniumoxide, magnesium oxide, silicon oxide, aluminum oxide). A metal alkoxidethin film can also be laminated with the metallic thin film. The metaloxide film or the metal alkoxide film can be laminated with each side ofthe metallic thin film. Different films can be laminated with both sidesof the metallic film.

The metal film has a thickness preferably in the range of 4 to 40 nm,more preferably in the range of 5 to 35 nm, and most preferably in therange of 6 to 30 nm.

The metal oxide film or the metal alkoxide film has a thicknesspreferably in the range of 20 to 300 nm, and more preferably in therange of 40 to 100 nm.

The electromagnetic wave shielding layer can be formed according to aspattering method, a vacuum evaporating method, an ion plating method, aplasma CVD method, a plasma PVD method or a superfine particle (of metalor metal oxide) coating method.

[Infrared ray shielding layer]

The infrared ray shielding layer preferably has a function of shieldinga near infrared ray of 800 to 1,200 nm. The infrared ray shielding layercan be formed of a resin mixture, which contains an infrared rayshielding component. Examples of the infrared ray shielding componentsinclude copper (described in Japanese Patent Provisional Publication No.6(1994)-118228), a copper compound or a phosphor compound (described inJapanese Patent Provisional Publication No. 62(1987)-5190), a coppercompound or a thiourea compound (described in Japanese PatentProvisional Publication No. 6(1994)-73197) and tungsten compound(described in U.S. Pat. No. 3,647,772). The resin mixture can be addedto the transparent support in place of forming the infrared rayshielding layer.

The thin silver layer described as the electromagnetic wave shieldinglayer can also function as the infrared ray shielding layer.

[Other layers]

The optical filter can further comprise a hard coating layer, a slipperylayer, a contamination preventive layer, an antistatic layer or anintermediate layer.

The hard coating layer preferably contains a cross-linked polymer, andcan be formed from acrylic, urethane or epoxy polymer or oligomer (e.g.,ultraviolet curable resin) or silica material.

On the top surface of the optical filter, a slippery layer may beprovided. The slippery layer gives slipperiness to the surface of theoptical filter, and improves the scratch resistance of the filter. Theslippery layer can be formed from polyorganosiloxane (e.g., siliconeoil), a natural wax, a petroleum wax, a metal salt of higher fatty acid,a fluorine lubricant or its derivative. The thickness of the slipperylayer is preferably in the range of 2 to 20 nm.

The contamination preventive layer can be made of a fluorine containingpolymer. The thickness of the contamination preventive layer ispreferably in the range of 2 to 100 nm, and more preferably in the rangeof 5 to 30 nm.

The layers such as the anti-reflection layers (middle, high, and lowrefractive index layers), the filter layer, the undercoating layer, thehard coating layer, the slippery layer, and other layers can be formedby known coating methods. Examples of the coating method include dipcoating, air knife coating, curtain coating, roller coating, wire barcoating, gravure coating, and extrusion coating with a hopper (describedin U.S. Pat. No. 2,681,294). Two or more layers may be simultaneouslyformed by coating. The method for simultaneous coating is described inU.S. Pat. Nos. 2,761,791, 2,941,898, 3,508,947, and 3,526,528; and“Coating Engineering” pp.253, written by Y. Harazaki, published byAsakura Shoten (1973).

[Use of optical filter]

The optical filter of the invention can be applied on a display devicesuch as a liquid crystal display (LCD), a plasma display panel (PDP), anelectroluminescence display (ELD) or a cathode ray tube display (CRT).In the case that the optical filter has an anti-reflection layer, theoptical filter is so arranged on the device that the surface opposite tothe low refractive index layer is attached to the display surface. Theoptical filter of the invention is particularly effective in a plasmadisplay panel (PDP).

A plasma display panel (PDP) comprises gas, glass substrates (front andback glass substrates), electrodes, electrode-lead member, thick filmprinting member, and phosphor. Each of the glass substrates is equippedwith the electrode and an insulating layer. On the back glass substrate,a phosphor layer is further provided. The gas is enclosed between thesubstrates.

A plasma display panel (PDP) is commercially available, and is describedin Japanese Patent Provisional Publication Nos. 5(1993)-205643 and9(1997)-306366.

In the display device such as the plasma display panel, the displaysurface is covered with the optical filter. The optical filter can bedirectly attached on the display surface. In the case that a plate isarranged in front of the display surface, the optical filter can beattached to the front (outside) surface of the front plate or the back(display side) surface of the plate.

EXAMPLE 1 Formation of Undercoating Layer

Both surfaces of a polyethylene terephthalate film (thickness: 175 μm)were subjected to a corona discharge treatment, and a latex ofstyrene-butadiene copolymer was applied on one of the surfaces to forman undercoating layer (thickness: 140 nm).

Formation of Second Undercoating Layer

On the undercoating layer, an aqueous gelatin solution containing aceticacid and glutaric aldehyde was applied to form a second undercoatinglayer (thickness: 50 nm).

Formation of Low Refractive Index Layer

To 2.50 g of a reactive fluorocarbon polymer (JN-7219, JSR Co., Ltd.),1.3 g of t-butanol was added. The mixture was stirred at roomtemperature for 10 minutes, and filtered through a polypropylene filter(porosity size: 1 μm) to prepare a coating solution for a low refractiveindex layer. The solution was applied on the support surface opposite tothe undercoating layers by using a bar coater, to form a layer (drythickness: 110 nm). The layer was dried and hardened at 120° C. for 30minutes to form a low refractive index layer.

Formation of Ultraviolet Absorbing Layer

With 10 g of the ultraviolet absorbing agent (I-6), 17 ml of a mixtureof the following high boiling point organic solvents (weight ratio of(1):(2) was 2:1) and 9 ml of ethyl acetate was mixed. The mixture washeated at 50° C. to dissolve the ultraviolet absorbing agent in thesolvents. The solution was added to 50 g of 20 wt. % aqueous gelatinsolution containing 6 ml of 10 wt. % aqueous solution of sodiumdodecylbenzenesulfonate. The mixture was stirred at 5,000 rpm for 20minutes. Water was added to the mixture to obtain 170 g of an emulsion.

High boiling point organic solvent (1)

High boiling point organic solvent (2)

The emulsion was coated on the second undercoating layer to form anultraviolet absorbing layer (dry thickness: 3.5 μm).

Formation of Filter Layer

To 180 g of 10 wt. % aqueous gelatin solution, 0.05 g of the methine dye(1) in an aggregated form and 0.15 g of the following dye (A) in anon-aggregated form were added. The mixture was filtered through apolypropylene filter (porosity size: 2 μm) to prepare a coating solutionfor a filter layer.

The coating solution for the filter layer was coated on the ultravioletabsorbing layer, and dried at 120° C. for 10 minutes to form a filterlayer (dry thickness: 3.5 μm). Thus, an optical filter was prepared.

The absorption spectrum of the obtained optical filter was measured. Thefilter layer has two absorption maximums at 533 nm and 594 nm. Thetransmittance at 533 nm was 65%, and the transmittance at 594 nm was30%. The half-width of the absorption maximum at 533 nm was 65 nm, andthe half-width of the absorption maximum at 594 nm was 35 nm.

EXAMPLE 2

The procedure of Example 1 was repeated except that 9.0 g of theultraviolet absorbing agent (I-3) and 1.0 g of the ultraviolet absorbingagent (I-11) were used in place of 10 g of the ultraviolet absorbingagent (I-6).

EXAMPLE 3

The procedure of Example 1 was repeated except that 4.5 g of theultraviolet absorbing agent (I-17), 4.5 g of the ultraviolet absorbingagent (I-2) and 1.0 g of the ultraviolet absorbing agent (I-9) were usedin place of 10 g of the ultraviolet absorbing agent (I-6).

EXAMPLE 4

The procedure of Example 1 was repeated except that 10 g of theultraviolet absorbing agent (I-2) was used in place of 10 g of theultraviolet absorbing agent (I-6).

EXAMPLE 5

The procedure of Example 1 was repeated except that 8.3 g of theultraviolet absorbing agent (II-1) and 1.7 g of the ultravioletabsorbing agent (II-11) were used in place of 10 g of the ultravioletabsorbing agent (I-6).

EXAMPLE 6

The procedure of Example 1 was repeated except that 10 g of theultraviolet absorbing agent (III-33) was used in place of 10 g of theultraviolet absorbing agent (I-6).

EXAMPLE 7

The procedure of Example 1 was repeated except that 9.0 g of theultraviolet absorbing agent (III-46) and 1.0 g of the ultravioletabsorbing agent (III-38) were used in place of 10 g of the ultravioletabsorbing agent (I-6).

EXAMPLE 8

The procedure of Example 1 was repeated except that 10 g of theultraviolet absorbing agent (III-5) was used in place of 10 g of theultraviolet absorbing agent (I-6).

COMPARISON EXAMPLE 1

The procedure of Example 1 was repeated except that the methine dye (1)was not used.

COMPARISON EXAMPLE 2

The procedure of Example 1 was repeated except that the ultravioletabsorbing layer was not formed.

Evaluation of Optical Filters

Each of the optical filters was attached to the front plate of acommercially available plasma display panel (PDS4202J-H, FujitsuLimited) by an adhesive in such a manner that the filter layer faces thefront plate.

The contract of the displayed image was measured. Further, white lightand red light were evaluated.

The optical filter was irradiated with light (from the side opposite tothe filter layer) by using a xenon lump (from which a UV filter had beenremoved) at 100,000 lx for 100 hours. The remaining ratio of the dye wasmeasured at 594 nm and at 530 nm (absorption maximums of the dyes). Theremaining ratio (light resistance) was defined by the following formula.

Remaining ratio=100×(100−transmittance after lightirradiation)/(100−transmittance before light irradiation) The resultsare set forth in Table 1.

TABLE 1 Ultraviolet absorbing agent Dye Color Resist. Ex. (amount) A NContrast W R 594 530 1 I-6 (10.0) (1) (A) 15:1 A A 90% 91% 2 I-3 (9.0) +I-11 (1.0) (1) (A) 15:1 A A 89% 91% 3 I-17 (4.5) + I-2 (4.5) + (1) (A)15:1 A A 89% 90% I-9 (1.0) 4 II-2 (10.0) (1) (A) 15:1 A A 91% 92% 5 II-1(8.3) + II-11 (1.7) (1) (A) 15:1 A A 90% 92% 6 III-33 (10.0) (1) (A)15:1 A A 90% 91% 7 III-46 (9.0) + (1) (A) 15:1 A A 88% 90% III-38 (1.0)8 III-5 (10.0) (1) (A) 15:1 A A 92% 93% C1   I-6 (10.0) — (A) 13:1 A B —91% C2   None (1) (A) 15:1 A A 68% 75%

(Remark)

Ex. C1: Comparison Example 1

Ex. C2: Comparison Example 2

Dye A: A methine dye in an aggregated form

Dye N: A dye in a non-aggregated form

Color W: White color of displayed light

Color R: Red color of displayed light

Color (A): Reproduced

Color (B): Not reproduced

Resist.: Light resistance measured at 594 nm and at 530 nm

EXAMPLE 9 Preparation of Transparent Support

With 45 weight parts of cellulose acetate (average acetic acid content:60.9%), 1.50 weight part of the ultraviolet absorbing agent (I-14), 2.75weight parts of triphenyl phosphate (plasticizer), 2.20 weight parts ofbiphenyldiphenyl phosphate (plasticizer), 232.72 weight parts ofmethylene chloride, 42.57 weight parts of methanol and 8.50 weight partsof n-butanol were mixed to prepare a solution (dope).

The dope was coated on a band casting machine (effective length: 6 m),and dried to prepare a transparent support (dry thickness: 100 μm).

Formation of Undercoating Layer

On one surface of the transparent support, a dispersion of gelatin inmethanol and acetone was coated, and dried to form an undercoating layer(thickness: 200 nm).

Formation of Hard Coating Layer

In 50 weight parts of methyl ethyl ketone, 25 weight parts ofdipentaerythrytol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.), 25weight parts of urethane acrylate oligomer (UV-6300B, Nippon SyntheticChemical Industry Co., Ltd.), 2 weight parts of a photopolymerizationinitiator (Irgacure 907, Ciba-Geigy) and 0.5 weight part of aphotosensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) were dissolvedto prepare a coating solution for a hard coating layer. The coatingsolution was applied on the support surface opposite to the undercoatinglayer by using a wired bar coater. The formed layer was dried, andirradiated with ultraviolet ray to form a hard coating layer (thickness:6 μm).

Formation of Filter Layer

To 180 g of 10 wt. % aqueous gelatin solution, 0.05 g of the methine dye(5) in an aggregated form and 0.15 g of the following dye (B) in anon-aggregated form were added. The mixture was filtered through apolypropylene filter (porosity size: 2 μm) to prepare a coating solutionfor a filter layer.

The coating solution for the filter layer was coated on the undercoatinglayer, and dried at 120° C. for 10 minutes to form a filter layer (drythickness: 3.5 μm). Thus, an optical filter was prepared.

The absorption spectrum of the obtained optical filter was measured. Thefilter layer has two absorption maximums at 532 nm and 591 nm. Thetransmittance at 532 nm was 75%, and the transmittance at 591 nm was21%. The half-width of the absorption maximum at 532 nm was 82 nm, andthe half-width of the absorption maximum at 591 nm was 24 nm.

EXAMPLE 10

The procedure of Example 9 was repeated except that 1.50 weight part ofthe ultraviolet absorbing agent (I-15) was used in place of 1.50 weightpart of the ultraviolet absorbing agent (I-14).

EXAMPLE 11

The procedure of Example 9 was repeated except that 1.20 weight part ofthe ultraviolet absorbing agent (1-6) and 0.30 weight part of theultraviolet absorbing agent (I-13) were used in place of 1.50 weightpart of the ultraviolet absorbing agent (I-14).

EXAMPLE 12

The procedure of Example 9 was repeated except that 1.50 weight part ofthe ultraviolet absorbing agent (II-9) was used in place of 1.50 weightpart of the ultraviolet absorbing agent (I-14).

EXAMPLE 13

The procedure of Example 9 was repeated except that 0.75 weight part ofthe ultraviolet absorbing agent (II-3) and 0.75 weight part of theultraviolet absorbing agent (II-18) were used in place of 1.50 weightpart of the ultraviolet absorbing agent (I-14).

EXAMPLE 14

The procedure of Example 9 was repeated except that 1.50 weight part ofthe ultraviolet absorbing agent (III-22) was used in place of 1.50weight part of the ultraviolet absorbing agent (I-14).

EXAMPLE 15

The procedure of Example 9 was repeated except that 1.50 weight part ofthe ultraviolet absorbing agent (III-5) was used in place of 1.50 weightpart of the ultraviolet absorbing agent (I-14).

EXAMPLE 8

The procedure of Example 9 was repeated except that 1.00 weight part ofthe ultraviolet absorbing agent (III-35) and 0.50 weight part of theultraviolet absorbing agent (III-41) were used in place of 1.50 weightpart of the ultraviolet absorbing agent (I-14).

COMPARISON EXAMPLE 3

The procedure of Example 1 was repeated except that the ultravioletabsorbing agent (I-14) was not formed.

Evaluation of Optical Filters

Each of the optical filters was attached to the front plate of acommercially available plasma display panel (PDS4202J-H, FujitsuLimited) by an adhesive in such a manner that the filter layer faces thefront plate.

The contract of the displayed image was measured. Further, white lightand red light were evaluated.

The optical filter was irradiated with light (from the side opposite tothe filter layer) by using a xenon lump (from which a UV filter had beenremoved) at 100,000 lx for 100 hours. The remaining ratio of the dye wasmeasured at 594 nm and at 530 nm (absorption maximums of the dyes). Theremaining ratio (light resistance) was defined by the following formula.

Remaining ratio=100×(100−transmittance after lightirradiation)/(100−transmittance before light irradiation)

The results are set forth in Table 2.

TABLE 2 Ultraviolet absorbing agent Dye Color Resist. Ex. (amount) A NContrast W R 594 530  9 I-14 (1.50) (5) (B) 15:1 A A 91% 96% 10 I-15(1.50) (5) (B) 15:1 A A 91% 95% 11 I-16 (1.20) + (5) (B) 15:1 A A 90%95% I-13 (0.30) 12 II-9 (1.50) (5) (B) 15:1 A A 90% 95% 13 II-3 (0.75) +(5) (B) 15:1 A A 91% 96% II-18 (0.75) 14 III-22 (1.50) (5) (B) 15:1 A A90% 95% 15 III-5 (1.50) (5) (B) 15:1 A A 93% 97% 16 III-35 (1.00) + (5)(B) 15:1 A A 90% 95% III-41 (0.50) C3 None (5) (B) 15:1 A A 62% 79%

(Remark)

Ex. C3: Comparison Example 3

Dye A: A methine dye in an aggregated form

Dye N: A dye in a non-aggregated form

Color W: White color of displayed light

Color R: Red color of displayed light

Color (A): Reproduced

Color (B): Not reproduced

Resist.: Light resistance measured at 594 nm and at 530 nm

EXAMPLE 17

A transparent support was prepared in the same manner as in Example 9was repeated except that the ultraviolet absorbing agent (I-9) was usedin place of the ultraviolet absorbing agent (I-14).

An undercoating layer, a hard coating layer and a low refractive indexlayer were formed on the transparent support in the same manner as inExample 9.

Formation of Infrared Ray Absorbing Layer

5 g of an infrared ray absorbing agent, 17 ml of the high boiling pointabsorbing agent (1) used in Example 1 and 10 ml of ethyl acetate weremixed, and heated at 50° C. to dissolve the infrared ray absorbing agentin the solvent. The solution was added to 50 g of 20 wt. % aqueousgelatin solution containing 6 ml of 10 wt. % aqueous solution of sodiumdodecylbenzenesulfonate. The mixture was stirred at 5,000 rpm for 20minutes. Water was added to the mixture to obtain 170 g of an emulsion.

The emulsion was coated on the undercoating layer to form an infraredray absorbing layer.

Formation of Filter Layer

To 180 g of 10 wt. % aqueous gelatin solution, 0.05 g of the methine dye(5) were added. The mixture was filtered through a polypropylene filter(porosity size: 2 μm) to prepare a coating solution for a filter layer.

The coating solution for the filter layer was coated on the undercoatinglayer, and dried at 120° C. for 10 minutes to form a filter layer (drythickness: 3.5 μm). Thus, an optical filter was prepared.

The absorption spectrum of the obtained optical filter was measured. Theresults are shown in FIG. 4.

As is shown in FIG. 4, he filter layer has two absorption maximums at527 nm and 593 nm. The transmittance at 527 nm was 70%, and thetransmittance at 593 nm was 30%. The half-width of the absorptionmaximum at 527 nm was 90 nm, and the half-width of the absorptionmaximum at 593 nm was 30 nm. Further, light within the ultravioletregion (350 nm or less) and the infrared region (700 nm or more) wascompletely cut by the filter. Further, the filter transmits light withinthe visible region (410 to 700 nm) except for the region of 500 to 550nm and 560 to 620 nm. All of the documents referenced herein are herebyincorporated by reference in each of their entireties herein.

I claim:
 1. An optical filter which comprises a transparent support anda filter layer containing a dye and a binder polymer, wherein the dye isa methine dye in an aggregated form, and wherein the transparentsupport, the filter layer or an optional layer further contains aultraviolet absorbing agent represented by the formula (I), (II), (III),(IV), (V), (VI), (VII) or (VIII):

in which the benzene rings a and b may have a substituent group;

in which Ar¹ is an aryl group or an aromatic heterocyclic group; —L— isa single bond or —O—; and the benzene ring c may have a substituentgroup;

in which the benzene ring d and the triazine ring e may have asubstituent group; and the benzene ring d may be condensed with anotheraromatic ring or a heterocyclic ring;

in which the benzene rings f and g may have a substituent group;

in which Ar² is an aryl group or an aromatic heterocyclic group; R¹ ishydrogen or an alkyl group; and each of R² and R³ independently iscyano, —COR¹³, —COOR¹⁴, —CONR¹⁵R¹⁶, —SO₂R¹⁷ or —SO₂NR¹⁸R¹⁹, wherein eachof R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ independently is hydrogen, analkyl group, a substituted alkyl group or an aryl group, or R² and R³are combined to form a five-membered or six-membered ring;

in which each of R⁴ and R⁵ independently is hydrogen, an alkyl group oran aryl group, or R⁴ and R⁵ are combined to form a five-membered orsix-membered ring; and each of R⁶ and R⁷ independently is cyano, —COR²⁰,—COOR²¹, —CONR²²R²³, —SO₂R²⁴ or —SO₂NR²⁵R²⁶, wherein each of R²⁰, R²¹,R²², R²³, R²⁴, R²⁵ and R²⁶ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group, or R⁶ and R⁷ are combined toform a five-membered or six-membered ring;

in which R⁸ is an alkyl group, a substituted alkyl group or an arylgroup; each of R⁹ and R¹⁰ independently is cyano, —COR²⁷, —COOR²⁸,—CONR²⁹R³⁰, —SO₂R³¹ or —SO₂NR³²R³³, wherein each of R²⁷, R²⁸, R²⁹, R³⁰,R³¹, R³² and R³³ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group, or R⁹ and R¹⁰ are combined toform a five-membered or six-membered ring; —X˜Y— is —CR³⁴R³⁵—CR³⁶R³⁷— or—CR³⁸═CR³⁹—, wherein each of R³⁴, R³⁵, R³⁶, R³⁷, R³⁸ and R³⁹independently is hydrogen, an alkyl group or an aryl group, or R³⁸ andR³⁹ are combined to form a benzene or naphthalene ring; —Z— is —O—, —S—,—NR⁴⁰—, —CR⁴¹R⁴²— or —CH═Ch—, wherein R⁴⁰ is an alkyl group, asubstituted alkyl group or an aryl group, and each of R⁴¹ and R⁴²independently is hydrogen or an alkyl group; and n is 0 or 1;

in which each of R¹¹ and R¹² independently is hydrogen, an alkyl groupor an aryl group, or R¹¹ and R¹² are combined to form a five-membered orsix-membered ring; the benzene rings h and i may have a substituentgroup; and the benzene rings h and i may be condensed with anotheraromatic ring or a heterocyclic ring.
 2. The optical filter as definedin claim 1, wherein the ultraviolet absorbing agent is an o-substitutedphenol represented by the formula (I), (II) or (III).
 3. The opticalfilter as defined in claim 1, wherein the longest wavelength at whichthe ultraviolet absorbing agent has an absorption maximum is within thewavelength region of 300 to 390 nm.
 4. The optical filter as defined inclaim 1, wherein the ultraviolet absorbing agent has an absorption, at awavelength of 50 nm longer than the longest wavelength at which theabsorbing agent has an absorption maximum, of less than 10% of theabsorption at the absorption maximum.
 5. The optical filter as definedin claim 1, wherein the aggregated dye has the absorption maximum withinthe wavelength region of 560 to 620 nm.
 6. The optical filter as definedin claim 1, wherein the filter layer further contains a dye in anon-aggregated from.
 7. The optical filter as defined in claim 6,wherein the non-aggregated dye has the absorption maximum within thewavelength region of 500 to 550 nm.
 8. The optical filter as defined inclaim 1, wherein the optical filter further comprises a low refractiveindex layer having a refractive index lower than a refractive index ofthe support.
 9. The optical filter as defined in claim 8, wherein theoptical filter comprises the filter layer, the transparent support andthe low refractive index layer in this order.
 10. The optical filter asdefined in claim 8, wherein the optical filter comprises the transparentsupport, the filter layer and the low refractive index layer in thisorder.
 11. A plasma display panel having a display surface covered withan optical filter which comprises a transparent and a filter layercontaining a dye and a binder polymer, wherein the dye is a methine dyein an aggregated form, and wherein the transparent support, the filterlayer or an optional layer further contains a ultraviolet absorbingagent represented by the formula (I), (II), (III), (IV), (V), (VI),(VII) or (VIII):

in which the benzene rings a and b may have a substituent group;

in which Ar¹ is an aryl group or an aromatic heterocyclic group; —L— isa single bond or —O—; and the benzene ring c may have a substituentgroup;

in which the benzene ring d and the triazine ring e may have asubstituent group; and the benzene ring d may be condensed with anotheraromatic ring or a heterocyclic ring;

in which the benzene rings f and g may have a substituent group;

in which Ar² is an aryl group or an aromatic heterocyclic group; R¹ ishydrogen or an alkyl group; and each of R² and R³ independently iscyano, —COR¹³, —COOR¹⁴, —CONR¹⁵R¹⁶, —SO₂R¹⁷ or —SO₂NR¹⁸R¹⁹, wherein eachof R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ independently is hydrogen, analkyl group, a substituted alkyl group or an aryl group, or R² and R³are combined to form a five-membered or six-membered ring;

in which each of R⁴ and R⁵ independently is hydrogen, an alkyl group oran aryl group, or R⁴ and R⁵ are combined to form a five-membered orsix-membered ring; and each of R⁶ and R⁷ independently is cyano, —COR²⁰,—COOR²¹, —CONR²²R²³, —SO₂R²⁴ or —SO₂NR²⁵R²⁶, wherein each of R²⁰, R²¹,R²², R²³, R²⁴, R²⁵ and R²⁶ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group, or R⁶ and R⁷ are combined toform a five-membered or six-membered ring;

in which R⁸ is an alkyl group, a substituted alkyl group or an arylgroup; each of R⁹ and R¹⁰ independently is cyano, —COR²⁷, —COOR²⁸,—CONR²⁹R³⁰, —SO₂R³¹ or —SO₂NR³²R³³, wherein each of R²⁷, R²⁸, R²⁹, R³⁰,R³¹, R³² and R³³ independently is hydrogen, an alkyl group, asubstituted alkyl group or an aryl group, or R⁹ and R¹⁰ are combined toform a five-membered or six-membered ring; —X˜Y— is —CR³⁴R³⁵—CR³⁶R³⁷— or—CR³⁸═CR³⁹—, wherein each of R³⁴, R³⁵, R³⁶, R³⁷, R³⁸ and R³⁹independently is hydrogen, an alkyl group or an aryl group, or R³⁸ andR³⁹ are combined to form a benzene or naphthalene ring; —Z— is —O—, —S—,—NR⁴⁰—, —CR⁴¹R⁴²— or —CH═Ch—, wherein R⁴⁰ is an alkyl group, asubstituted alkyl group or an aryl group, and each of R⁴¹ and R⁴²independently is hydrogen or an alkyl group; and n is 0 or 1;

in which each of R¹¹ and R¹² independently is hydrogen, an alkyl groupor an aryl group, or R¹¹ and R¹² are combined to form a five-membered orsix-membered ring; the benzene rings h and i may have a substituentgroup; and the benzene rings h and i may be condensed with anotheraromatic ring or a heterocyclic ring.
 12. The plasma display panel asdefined in claim 11, wherein the ultraviolet absorbing agent is ano-substituted phenol represented by the formula (I), (II) or (III).